1. What is a chemical reaction?
A chemical reaction forms new substances.
2. Why do chemical reactions occur?
To achieve stability by bond changes.
3. What is a chemical equation?
A chemical equation shows reactants and products.
4. Why use a chemical equation?
It represents a reaction symbolically.
5. What are reactants?
Reactants are substances that react.
6. What are products?
Products are substances formed in reactions.
7. Why balance chemical equations?
To obey the law of mass conservation.
8. What is the law of conservation of mass?
Mass of reactants equals mass of products.
9. What does a balanced equation show?
Equal atoms on both sides.
10. Why use arrows in equations?
Arrows show the direction of reaction.
11. What is a combination reaction?
Two or more substances form one product.
12. Why is a combination reaction exothermic?
It releases energy forming bonds.
13. What is an example of a combination reaction?
C + O 2 → C O 2.
14. Why is C O 2 formed from C and O 2?
Carbon and oxygen combine.
15. What is a decomposition reaction?
A compound breaks into simpler substances.
16. Why is decomposition endothermic?
It absorbs energy to break bonds.
17. What is an example of decomposition?
2 H 2 O → 2 H 2 + O 2.
18. Why does H 2 O decompose?
Energy breaks water into gases.
19. What is a displacement reaction?
A more reactive element displaces another.
20. Why does displacement occur?
Due to differences in reactivity.
21. What is an example of displacement?
Z n + C u S O 4 → Z n S O 4 + C u.
22. Why does Z n displace C u?
Zinc is more reactive than copper.
23. What is a double displacement reaction?
Ions exchange to form new compounds.
24. Why do double displacement reactions occur?
To form a precipitate or gas.
25. What is an example of double displacement?
N a C l + A g N O 3 → A g C l + N a N O 3.
26. Why does A g C l precipitate?
It is insoluble in water.
27. What is an oxidation reaction?
Oxidation involves loss of electrons.
28. Why is oxygen gain oxidation?
It increases the oxidation state.
29. What is a reduction reaction?
Reduction involves gain of electrons.
30. Why is oxygen loss reduction?
It decreases the oxidation state.
31. What is a redox reaction?
A reaction with both oxidation and reduction.
32. Why are redox reactions common?
Electron transfer drives many reactions.
33. What is an example of a redox reaction?
C u O + H 2 → C u + H 2 O.
34. Why is C u O reduced?
It loses oxygen to form C u.
35. What is corrosion?
Corrosion is metal deterioration by reaction.
36. Why does iron corrode?
It reacts with oxygen and moisture.
37. What is rust?
Rust is F e 2 O 3 · x H 2 O.
38. Why is rusting harmful?
It weakens iron structures.
39. What is rancidity?
Rancidity is oxidation of food oils.
40. Why do foods go rancid?
Oils react with oxygen over time.
41. What prevents rancidity?
Antioxidants or airtight storage.
42. Why store food in vacuum packs?
To reduce oxygen exposure.
43. What is the symbol for hydrogen gas?
H 2.
44. Why is H 2 diatomic?
Hydrogen forms stable H 2 molecules.
45. What is the symbol for oxygen gas?
O 2.
46. Why is O 2 diatomic?
Oxygen forms stable O 2 molecules.
47. What is the formula for water?
H 2 O.
48. Why is water H 2 O?
It has two hydrogens, one oxygen.
49. What is the formula for carbon dioxide?
C O 2.
50. Why is C O 2 formed?
Carbon bonds with two oxygens.
51. What is a precipitate?
A precipitate is an insoluble solid.
52. Why do precipitates form?
Ions combine to form insoluble compounds.
53. What is an exothermic reaction?
It releases heat energy.
54. Why is burning exothermic?
It releases energy as heat.
55. What is an endothermic reaction?
It absorbs heat energy.
56. Why is decomposition endothermic?
It requires energy to break bonds.
57. What is the reaction of magnesium with oxygen?
2 M g + O 2 → 2 M g O.
58. Why does M g O form?
Magnesium combines with oxygen.
59. What type is M g + O 2 → M g O?
Combination reaction.
60. Why is M g O white?
It’s a property of magnesium oxide.
61. What is the decomposition of C a C O 3?
C a C O 3 → C a O + C O 2.
62. Why does C a C O 3 decompose?
Heat breaks it into simpler compounds.
63. What type is C a C O 3 decomposition?
Decomposition reaction.
64. Why is C a O formed?
It’s a stable product of decomposition.
65. What is F e + C u S O 4 reaction?
F e + C u S O 4 → F e S O 4 + C u.
66. Why does F e displace C u?
Iron is more reactive than copper.
67. What type is F e + C u S O 4?
Displacement reaction.
68. Why is C u deposited?
Iron replaces copper in solution.
69. What is N a 2 S O 4 + B a C l 2 reaction?
N a 2 S O 4 + B a C l 2 → B a S O 4 + 2 N a C l.
70. Why does B a S O 4 precipitate?
It’s insoluble in water.
71. What type is N a 2 S O 4 + B a C l 2?
Double displacement reaction.
72. Why do ions exchange?
To form stable compounds.
73. What is burning of methane?
C H 4 + 2 O 2 → C O 2 + 2 H 2 O.
74. Why is methane burning exothermic?
It releases heat and light.
75. What type is methane burning?
Redox reaction.
76. Why is C O 2 formed?
Carbon bonds with oxygen.
77. What is electrolysis of water?
78. Why does water split?
Electricity breaks water’s bonds.
79. What type is water electrolysis?
80. Why is O 2 produced?
Oxygen atoms combine after splitting.
81. What is Z n + H 2 S O 4 reaction?
Z n + H 2 S O 4 → Z n S O 4 + H 2.
82. Why does H 2 gas form?
Zinc displaces hydrogen.
83. What type is Z n + H 2 S O 4?
84. Why is Z n S O 4 formed?
Zinc bonds with sulfate ions.
85. What is P b ( N O 3 ) 2 + K I reaction?
P b ( N O 3 ) 2 + 2 K I → P b I 2 + 2 K N O 3.
86. Why does P b I 2 precipitate?
87. What type is P b ( N O 3 ) 2 + K I?
88. Why do nitrates exchange?
To form stable products.
89. What is 2 H 2 + O 2 reaction?
2 H 2 + O 2 → 2 H 2 O.
90. Why is H 2 O formed?
Hydrogen combines with oxygen.
91. What type is 2 H 2 + O 2?
92. Why is it exothermic?
It releases heat forming water.
93. What is thermal decomposition of F e S O 4?
2 F e S O 4 → F e 2 O 3 + S O 2 + S O 3.
94. Why does F e S O 4 decompose?
Heat breaks its bonds.
95. What type is F e S O 4 decomposition?
96. Why is S O 2 formed?
It’s a product of sulfate breakdown.
97. What is C u + 2 A g N O 3 reaction?
C u + 2 A g N O 3 → C u ( N O 3 ) 2 + 2 A g.
98. Why does C u displace A g?
Copper is more reactive than silver.
99. What type is C u + A g N O 3?
100. Why is A g deposited?
Copper replaces silver in solution.
101. What is K C l + A g N O 3 reaction?
K C l + A g N O 3 → A g C l + K N O 3.
102. Why does A g C l form?
It’s an insoluble precipitate.
103. What type is K C l + A g N O 3?
104. Why do ions swap?
105. What is 2 N a + 2 H 2 O reaction?
2 N a + 2 H 2 O → 2 N a O H + H 2.
106. Why does H 2 gas evolve?
Sodium displaces hydrogen.
107. What type is N a + H 2 O?
108. Why is N a O H formed?
Sodium reacts with water.
109. What is burning of sulphur?
S + O 2 → S O 2.
110. Why is S O 2 formed?
Sulphur combines with oxygen.
111. What type is S + O 2?
112. Why is it exothermic?
It releases heat.
113. What is decomposition of H 2 O 2?
2 H 2 O 2 → 2 H 2 O + O 2.
114. Why does H 2 O 2 decompose?
It breaks into stable products.
115. What type is H 2 O 2 decomposition?
116. Why is O 2 released?
It’s a product of breakdown.
117. What is M n O 2 role in H 2 O 2 decomposition?
M n O 2 acts as a catalyst.
118. Why use a catalyst?
It speeds up the reaction.
119. What is Z n + H C l reaction?
Z n + 2 H C l → Z n C l 2 + H 2.
120. Why does H 2 form?
121. What type is Z n + H C l?
122. Why is Z n C l 2 formed?
Zinc bonds with chloride ions.
123. What is N a O H + H C l reaction?
N a O H + H C l → N a C l + H 2 O.
124. Why is N a C l formed?
Sodium and chloride ions combine.
125. What type is N a O H + H C l?
126. Why is it neutralization?
Acid and base form salt and water.
127. What is burning of carbon?
128. Why is C O 2 produced?
129. What type is C + O 2?
130. Why is it exothermic?
131. What is decomposition of N a 2 C O 3?
N a 2 C O 3 does not decompose easily.
132. Why is N a 2 C O 3 stable?
It requires high energy to break.
133. What is C a O + H 2 O reaction?
C a O + H 2 O → C a ( O H ) 2.
134. Why is C a ( O H ) 2 formed?
Calcium oxide reacts with water.
135. What type is C a O + H 2 O?
136. Why is it exothermic?
It releases heat forming hydroxide.
137. What is A l + C u C l 2 reaction?
2 A l + 3 C u C l 2 → 2 A l C l 3 + 3 C u.
138. Why does A l displace C u?
Aluminium is more reactive.
139. What type is A l + C u C l 2?
140. Why is C u formed?
Aluminium replaces copper.
141. What is K O H + H N O 3 reaction?
K O H + H N O 3 → K N O 3 + H 2 O.
142. Why is K N O 3 formed?
Potassium and nitrate ions combine.
143. What type is K O H + H N O 3?
144. Why is it neutralization?
It forms salt and water.
145. What is 2 P b O + C reaction?
2 P b O + C → 2 P b + C O 2.
146. Why is P b formed?
Carbon reduces lead oxide.
147. What type is P b O + C?
148. Why is C oxidized?
It gains oxygen to form C O 2.
149. What is S O 2 + O 2 reaction?
2 S O 2 + O 2 → 2 S O 3.
150. Why is S O 3 formed?
Sulphur dioxide combines with oxygen.
151. What type is S O 2 + O 2?
152. Why is it oxidation?
Sulphur gains more oxygen.
153. What is decomposition of A g C l?
2 A g C l → 2 A g + C l 2.
154. Why does A g C l decompose?
Light breaks it into elements.
155. What type is A g C l decomposition?
156. Why is C l 2 formed?
Chlorine atoms combine after splitting.
157. What is F e + H 2 O reaction?
F e + H 2 O → F e 3 O 4 + H 2.
158. Why is F e 3 O 4 formed?
Iron reacts with steam.
159. What type is F e + H 2 O?
160. Why is H 2 released?
Iron displaces hydrogen.
161. What is N a 2 C O 3 + H C l reaction?
N a 2 C O 3 + 2 H C l → 2 N a C l + H 2 O + C O 2.
162. Why is C O 2 evolved?
Carbonate reacts with acid.
163. What type is N a 2 C O 3 + H C l?
164. Why is N a C l formed?
165. What is burning of H 2 S?
2 H 2 S + 3 O 2 → 2 H 2 O + 2 S O 2.
166. Why is S O 2 formed?
Sulphur bonds with oxygen.
167. What type is H 2 S burning?
168. Why is H 2 O produced?
Hydrogen bonds with oxygen.
169. What is C a ( O H ) 2 + C O 2 reaction?
C a ( O H ) 2 + C O 2 → C a C O 3 + H 2 O.
170. Why is C a C O 3 formed?
Calcium hydroxide reacts with carbon dioxide.
171. What type is C a ( O H ) 2 + C O 2?
172. Why is H 2 O formed?
It’s a byproduct of reaction.
173. What is M g + H 2 S O 4 reaction?
M g + H 2 S O 4 → M g S O 4 + H 2.
174. Why does H 2 evolve?
Magnesium displaces hydrogen.
175. What type is M g + H 2 S O 4?
176. Why is M g S O 4 formed?
Magnesium bonds with sulfate.
177. What is B a C l 2 + N a 2 S O 4 reaction?
B a C l 2 + N a 2 S O 4 → B a S O 4 + 2 N a C l.
178. Why is B a S O 4 insoluble?
It forms a precipitate.
179. What type is B a C l 2 + N a 2 S O 4?
180. Why do ions exchange?
181. What is 2 C u + O 2 reaction?
2 C u + O 2 → 2 C u O.
182. Why is C u O formed?
Copper combines with oxygen.
183. What type is C u + O 2?
184. Why is it oxidation?
Copper gains oxygen.
185. What is decomposition of K C l O 3?
2 K C l O 3 → 2 K C l + 3 O 2.
186. Why does K C l O 3 decompose?
Heat breaks it into products.
187. What type is K C l O 3 decomposition?
188. Why is O 2 formed?
189. What is C a + H 2 O reaction?
C a + 2 H 2 O → C a ( O H ) 2 + H 2.
190. Why does H 2 form?
Calcium displaces hydrogen.
191. What type is C a + H 2 O?
192. Why is C a ( O H ) 2 formed?
Calcium reacts with water.
193. What is K 2 C O 3 + H 2 S O 4 reaction?
K 2 C O 3 + H 2 S O 4 → K 2 S O 4 + H 2 O + C O 2.
194. Why is C O 2 produced?
195. What type is K 2 C O 3 + H 2 S O 4?
196. Why is K 2 S O 4 formed?
Potassium bonds with sulfate.
197. What is burning of C 2 H 5 O H?
C 2 H 5 O H + 3 O 2 → 2 C O 2 + 3 H 2 O.
198. Why is C O 2 formed?
199. What type is C 2 H 5 O H burning?
200. Why is it exothermic?
201. What is S O 2 + H 2 S reaction?
2 H 2 S + S O 2 → 3 S + 2 H 2 O.
202. Why is S formed?
Sulphur dioxide reduces hydrogen sulphide.
203. What type is S O 2 + H 2 S?
204. Why is H 2 O produced?
It’s a reaction byproduct.
205. What is C a C O 3 + H C l reaction?
C a C O 3 + 2 H C l → C a C l 2 + H 2 O + C O 2.
206. Why is C O 2 evolved?
Acid reacts with carbonate.
207. What type is C a C O 3 + H C l?
208. Why is C a C l 2 formed?
Calcium bonds with chloride.
209. What is 2 A g B r decomposition?
2 A g B r → 2 A g + B r 2.
210. Why does A g B r decompose?
Light breaks its bonds.
211. What type is A g B r decomposition?
212. Why is B r 2 formed?
Bromine atoms combine after splitting.
213. What is N a + C l 2 reaction?
2 N a + C l 2 → 2 N a C l.
214. Why is N a C l formed?
Sodium combines with chlorine.
215. What type is N a + C l 2?
216. Why is it exothermic?
It releases heat forming salt.
217. What is F e S O 4 + N a O H reaction?
F e S O 4 + 2 N a O H → F e ( O H ) 2 + N a 2 S O 4.
218. Why does F e ( O H ) 2 precipitate?
219. What type is F e S O 4 + N a O H?
220. Why is N a 2 S O 4 formed?
Sodium bonds with sulfate.
221. What is C u S O 4 + N a 2 C O 3 reaction?
C u S O 4 + N a 2 C O 3 → C u C O 3 + N a 2 S O 4.
222. Why does C u C O 3 precipitate?
223. What type is C u S O 4 + N a 2 C O 3?
224. Why is N a 2 S O 4 formed?
225. What is M g O + C O 2 reaction?
M g O + C O 2 → M g C O 3.
226. Why is M g C O 3 formed?
Magnesium oxide reacts with carbon dioxide.
227. What type is M g O + C O 2?
228. Why is it stable?
M g C O 3 is a stable compound.
229. What is Z n O + C reaction?
Z n O + C → Z n + C O.
230. Why is Z n formed?
Carbon reduces zinc oxide.
231. What type is Z n O + C?
232. Why is C O formed?
233. What is K I + C l 2 reaction?
2 K I + C l 2 → 2 K C l + I 2.
234. Why is I 2 formed?
Chlorine displaces iodine.
235. What type is K I + C l 2?
236. Why is C l 2 more reactive?
Chlorine is higher in reactivity series.
237. What is C a S O 4 + N a C l reaction?
C a S O 4 + N a C l → No reaction.
238. Why no reaction with C a S O 4?
Products are soluble, no precipitate.
239. What is N a H C O 3 + H C l reaction?
N a H C O 3 + H C l → N a C l + H 2 O + C O 2.
240. Why is C O 2 evolved?
Bicarbonate reacts with acid.
241. What type is N a H C O 3 + H C l?
242. Why is N a C l formed?
Sodium bonds with chloride.
243. What is burning of C 3 H 8?
C 3 H 8 + 5 O 2 → 3 C O 2 + 4 H 2 O.
244. Why is C O 2 formed?
245. What type is C 3 H 8 burning?
246. Why is it exothermic?
247. What is decomposition of C u C O 3?
C u C O 3 → C u O + C O 2.
248. Why does C u C O 3 decompose?
249. What type is C u C O 3 decomposition?
250. Why is C u O formed?
It’s a stable product.
251. What is A l + F e 2 O 3 reaction?
2 A l + F e 2 O 3 → A l 2 O 3 + 2 F e.
252. Why does A l displace F e?
253. What type is A l + F e 2 O 3?
254. Why is F e formed?
Aluminium reduces iron oxide.
255. What is N a 2 S O 4 + C a C l 2 reaction?
N a 2 S O 4 + C a C l 2 → C a S O 4 + 2 N a C l.
256. Why does C a S O 4 precipitate?
It’s less soluble in water.
257. What type is N a 2 S O 4 + C a C l 2?
258. Why is N a C l formed?
259. What is C a O + S O 2 reaction?
C a O + S O 2 → C a S O 3.
260. Why is C a S O 3 formed?
Calcium oxide reacts with sulphur dioxide.
261. What type is C a O + S O 2?
262. Why is it stable?
C a S O 3 is a stable compound.
263. What is H 2 + C l 2 reaction?
H 2 + C l 2 → 2 H C l.
264. Why is H C l formed?
Hydrogen combines with chlorine.
265. What type is H 2 + C l 2?
266. Why is it exothermic?
267. What is C u S O 4 + H 2 S reaction?
C u S O 4 + H 2 S → C u S + H 2 S O 4.
268. Why does C u S precipitate?
269. What type is C u S O 4 + H 2 S?
270. Why is H 2 S O 4 formed?
Hydrogen bonds with sulfate.
271. What is decomposition of N H 4 C l?
N H 4 C l → N H 3 + H C l.
272. Why does N H 4 C l decompose?
273. What type is N H 4 C l decomposition?
274. Why is N H 3 formed?
275. What is K + H 2 O reaction?
2 K + 2 H 2 O → 2 K O H + H 2.
276. Why does H 2 evolve?
Potassium displaces hydrogen.
277. What type is K + H 2 O?
278. Why is K O H formed?
Potassium reacts with water.
279. What is M g C O 3 + H 2 S O 4 reaction?
M g C O 3 + H 2 S O 4 → M g S O 4 + H 2 O + C O 2.
280. Why is C O 2 evolved?
281. What type is M g C O 3 + H 2 S O 4?
282. Why is M g S O 4 formed?
283. What is burning of C 4 H 10?
2 C 4 H 10 + 13 O 2 → 8 C O 2 + 10 H 2 O.
284. Why is C O 2 formed?
285. What type is C 4 H 10 burning?
286. Why is it exothermic?
287. What is C u O + N H 3 reaction?
3 C u O + 2 N H 3 → 3 C u + N 2 + 3 H 2 O.
288. Why is C u formed?
Ammonia reduces copper oxide.
289. What type is C u O + N H 3?
290. Why is N 2 formed?
Nitrogen atoms combine after oxidation.
291. What is N a B r + C l 2 reaction?
2 N a B r + C l 2 → 2 N a C l + B r 2.
292. Why is B r 2 formed?
Chlorine displaces bromine.
293. What type is N a B r + C l 2?
294. Why is C l 2 reactive?
It’s higher in reactivity series.
295. What is C a ( O H ) 2 + H N O 3 reaction?
C a ( O H ) 2 + 2 H N O 3 → C a ( N O 3 ) 2 + 2 H 2 O.
296. Why is C a ( N O 3 ) 2 formed?
Calcium bonds with nitrate.
297. What type is C a ( O H ) 2 + H N O 3?
298. Why is it neutralization?
Base and acid form salt and water.
299. What is F e 2 O 3 + C O reaction?
F e 2 O 3 + 3 C O → 2 F e + 3 C O 2.
300. Why is F e formed?
Carbon monoxide reduces iron oxide.
301. What type is F e 2 O 3 + C O?
302. Why is C O 2 formed?
Carbon monoxide is oxidized.
303. What is P + O 2 reaction?
4 P + 5 O 2 → 2 P 2 O 5.
304. Why is P 2 O 5 formed?
Phosphorus combines with oxygen.
305. What type is P + O 2?
306. Why is it exothermic?
307. What is decomposition of Z n C O 3?
Z n C O 3 → Z n O + C O 2.
308. Why does Z n C O 3 decompose?
309. What type is Z n C O 3 decomposition?
310. Why is Z n O formed?
311. What is M g + Z n S O 4 reaction?
M g + Z n S O 4 → M g S O 4 + Z n.
312. Why does M g displace Z n?
Magnesium is more reactive.
313. What type is M g + Z n S O 4?
314. Why is Z n formed?
Magnesium replaces zinc.
315. What is N a O H + H 2 S O 4 reaction?
2 N a O H + H 2 S O 4 → N a 2 S O 4 + 2 H 2 O.
316. Why is N a 2 S O 4 formed?
317. What type is N a O H + H 2 S O 4?
318. Why is it neutralization?
319. What is C u + H 2 S O 4 reaction?
C u + H 2 S O 4 → No reaction.
320. Why no reaction with C u?
Copper is less reactive than hydrogen.
321. What is C + H 2 O reaction?
C + H 2 O → C O + H 2.
322. Why is C O formed?
Carbon reacts with steam.
323. What type is C + H 2 O?
324. Why is H 2 produced?
Water is reduced by carbon.
325. What is K 2 S O 4 + B a C l 2 reaction?
K 2 S O 4 + B a C l 2 → B a S O 4 + 2 K C l.
326. Why does B a S O 4 precipitate?
327. What type is K 2 S O 4 + B a C l 2?
328. Why is K C l formed?
Potassium bonds with chloride.
329. What is burning of N H 3?
4 N H 3 + 3 O 2 → 2 N 2 + 6 H 2 O.
330. Why is N 2 formed?
331. What type is N H 3 burning?
332. Why is H 2 O produced?
333. What is decomposition of H g O?
2 H g O → 2 H g + O 2.
334. Why does H g O decompose?
335. What type is H g O decomposition?
336. Why is H g formed?
337. What is C a + H C l reaction?
C a + 2 H C l → C a C l 2 + H 2.
338. Why does H 2 evolve?
339. What type is C a + H C l?
340. Why is C a C l 2 formed?
341. What is N a 2 C O 3 + H 2 S O 4 reaction?
N a 2 C O 3 + H 2 S O 4 → N a 2 S O 4 + H 2 O + C O 2.
342. Why is C O 2 evolved?
343. What type is N a 2 C O 3 + H 2 S O 4?
344. Why is N a 2 S O 4 formed?
345. What is S + O 2 reaction?
346. Why is S O 2 formed?
347. What type is S + O 2?
348. Why is it exothermic?
349. What is C u S O 4 + N a O H reaction?
C u S O 4 + 2 N a O H → C u ( O H ) 2 + N a 2 S O 4.
350. Why does C u ( O H ) 2 precipitate?
351. What type is C u S O 4 + N a O H?
352. Why is N a 2 S O 4 formed?
353. What is Z n C O 3 + H C l reaction?
Z n C O 3 + 2 H C l → Z n C l 2 + H 2 O + C O 2.
354. Why is C O 2 evolved?
355. What type is Z n C O 3 + H C l?
356. Why is Z n C l 2 formed?
Zinc bonds with chloride.
357. What is burning of C 2 H 2?
2 C 2 H 2 + 5 O 2 → 4 C O 2 + 2 H 2 O.
358. Why is C O 2 formed?
359. What type is C 2 H 2 burning?
360. Why is it exothermic?
361. What is decomposition of P b ( N O 3 ) 2?
2 P b ( N O 3 ) 2 → 2 P b O + 4 N O 2 + O 2.
362. Why does P b ( N O 3 ) 2 decompose?
363. What type is P b ( N O 3 ) 2 decomposition?
364. Why is N O 2 formed?
It’s a product of nitrate breakdown.
365. What is A g N O 3 + N a C l reaction?
A g N O 3 + N a C l → A g C l + N a N O 3.
366. Why does A g C l precipitate?
367. What type is A g N O 3 + N a C l?
368. Why is N a N O 3 formed?
Sodium bonds with nitrate.
369. What is F e + S reaction?
F e + S → F e S.
370. Why is F e S formed?
Iron combines with sulphur.
371. What type is F e + S?
372. Why is it exothermic?
373. What is M g + O 2 reaction?
374. Why is M g O formed?
375. What type is M g + O 2?
376. Why is it bright?
It releases light energy.
377. What is C u S O 4 + F e reaction?
C u S O 4 + F e → F e S O 4 + C u.
378. Why does F e displace C u?
Iron is more reactive.
379. What type is C u S O 4 + F e?
380. Why is C u formed?
Iron replaces copper.
381. What is N a O H + H N O 3 reaction?
N a O H + H N O 3 → N a N O 3 + H 2 O.
382. Why is N a N O 3 formed?
383. What type is N a O H + H N O 3?
384. Why is it neutralization?
385. What is C O + O 2 reaction?
2 C O + O 2 → 2 C O 2.
386. Why is C O 2 formed?
Carbon monoxide combines with oxygen.
387. What type is C O + O 2?
388. Why is it oxidation?
Carbon gains oxygen.
389. What is decomposition of N a C l O 3?
2 N a C l O 3 → 2 N a C l + 3 O 2.
390. Why does N a C l O 3 decompose?
391. What type is N a C l O 3 decomposition?
392. Why is O 2 formed?
393. What is Z n + A g N O 3 reaction?
Z n + 2 A g N O 3 → Z n ( N O 3 ) 2 + 2 A g.
394. Why does Z n displace A g?
Zinc is more reactive.
395. What type is Z n + A g N O 3?
396. Why is A g formed?
Zinc replaces silver.
397. What is K O H + H C l reaction?
K O H + H C l → K C l + H 2 O.
398. Why is K C l formed?
399. What type is K O H + H C l?
400. Why is it neutralization?
401. What is C u O + H 2 reaction?
402. Why is C u formed?
Hydrogen reduces copper oxide.
403. What type is C u O + H 2?
404. Why is H 2 O formed?
405. What is C a C O 3 decomposition?
406. Why does C a C O 3 decompose?
407. What type is C a C O 3 decomposition?
408. Why is C a O formed?
409. What is A l + H 2 S O 4 reaction?
2 A l + 3 H 2 S O 4 → A l 2 ( S O 4 ) 3 + 3 H 2.
410. Why does H 2 evolve?
Aluminium displaces hydrogen.
411. What type is A l + H 2 S O 4?
412. Why is A l 2 ( S O 4 ) 3 formed?
Aluminium bonds with sulfate.
413. What is N a 2 S O 4 + P b ( N O 3 ) 2 reaction?
N a 2 S O 4 + P b ( N O 3 ) 2 → P b S O 4 + 2 N a N O 3.
414. Why does P b S O 4 precipitate?
415. What type is N a 2 S O 4 + P b ( N O 3 ) 2?
416. Why is N a N O 3 formed?
417. What is N 2 + 3 H 2 reaction?
N 2 + 3 H 2 → 2 N H 3.
418. Why is N H 3 formed?
Nitrogen combines with hydrogen.
419. What type is N 2 + H 2?
420. Why is a catalyst used?
It speeds up ammonia formation.
421. What is corrosion of copper?
Copper forms C u C O 3 · C u ( O H ) 2.
422. Why does copper turn green?
It reacts with air and moisture.
423. What is corrosion of silver?
Silver forms A g 2 S.
424. Why does silver tarnish?
It reacts with sulphur compounds.
425. What prevents corrosion?
Painting or galvanizing metals.
426. Why use galvanizing?
Zinc protects iron from rusting.
427. What is rancidity in oils?
Oils oxidize, causing bad smell.
428. Why do chips go rancid?
Fats react with oxygen.
429. What is an antioxidant?
It prevents oxidation in food.
430. Why flush chips with nitrogen?
To exclude oxygen and prevent rancidity.
431. What is the reactivity series?
A list of metals by reactivity.
432. Why is potassium most reactive?
It easily loses electrons.
433. What is the least reactive metal?
Gold is least reactive.
434. Why is gold unreactive?
It resists electron loss.
435. What is H 2 S O 4 formula?
H 2 S O 4 is sulphuric acid.
436. Why is H 2 S O 4 an acid?
It donates H⁺ ions.
437. What is N a O H formula?
N a O H is sodium hydroxide.
438. Why is N a O H a base?
It releases O H⁻ ions.
439. What is C a C O 3 formula?
C a C O 3 is calcium carbonate.
440. Why is C a C O 3 used?
It neutralizes acids.
441. What is M g O formula?
M g O is magnesium oxide.
442. Why is M g O basic?
It reacts with acids.
443. What is F e S O 4 formula?
F e S O 4 is iron(II) sulphate.
444. Why is F e S O 4 green?
Due to iron(II) ions.
445. What is C u S O 4 formula?
C u S O 4 is copper(II) sulphate.
446. Why is C u S O 4 blue?
Due to hydrated copper ions.
447. What is Z n S O 4 formula?
Z n S O 4 is zinc sulphate.
448. Why is Z n S O 4 used?
In galvanizing and supplements.
449. What is A g N O 3 formula?
A g N O 3 is silver nitrate.
450. Why is A g N O 3 used?
In photography and medicine.
451. What is N a 2 C O 3 formula?
N a 2 C O 3 is sodium carbonate.
452. Why is N a 2 C O 3 basic?
453. What is K C l formula?
K C l is potassium chloride.
454. Why is K C l used?
In fertilizers and salts.
455. What is B a S O 4 formula?
B a S O 4 is barium sulphate.
456. Why is B a S O 4 insoluble?
It has low solubility.
457. What is P b I 2 formula?
P b I 2 is lead(II) iodide.
458. Why is P b I 2 yellow?
Due to lead iodide’s structure.
459. What is C a ( O H ) 2 formula?
C a ( O H ) 2 is calcium hydroxide.
460. Why is C a ( O H ) 2 used?
In limewater and construction.
461. What is H 2 O 2 formula?
H 2 O 2 is hydrogen peroxide.
462. Why is H 2 O 2 unstable?
It decomposes easily.
463. What is K C l O 3 formula?
K C l O 3 is potassium chlorate.
464. Why is K C l O 3 used?
In matches and explosives.
465. What is A g C l formula?
A g C l is silver chloride.
466. Why is A g C l white?
Due to its crystal structure.
467. What is N a H C O 3 formula?
N a H C O 3 is sodium bicarbonate.
468. Why is N a H C O 3 used?
In baking and antacids.
469. What is F e 2 O 3 formula?
F e 2 O 3 is iron(III) oxide.
470. Why is F e 2 O 3 red?
Due to iron’s oxidation state.
471. What is C u O formula?
C u O is copper(II) oxide.
472. Why is C u O black?
Due to copper’s oxidation state.
473. What is Z n O formula?
Z n O is zinc oxide.
474. Why is Z n O white?
475. What is A l 2 O 3 formula?
A l 2 O 3 is aluminium oxide.
476. Why is A l 2 O 3 used?
In ceramics and abrasives.
477. What is N H 3 formula?
N H 3 is ammonia.
478. Why is N H 3 basic?
It accepts H⁺ ions.
479. What is C H 4 formula?
C H 4 is methane.
480. Why is C H 4 flammable?
It reacts with oxygen.
481. What is C 2 H 5 O H formula?
C 2 H 5 O H is ethanol.
482. Why is ethanol used?
In fuels and disinfectants.
483. What is C O formula?
C O is carbon monoxide.
484. Why is C O toxic?
It binds to haemoglobin.
485. What is S O 2 formula?
S O 2 is sulphur dioxide.
486. Why is S O 2 harmful?
It causes acid rain.
487. What is N O 2 formula?
N O 2 is nitrogen dioxide.
488. Why is N O 2 brown?
Due to its molecular structure.
489. What is H C l formula?
H C l is hydrochloric acid.
490. Why is H C l acidic?
491. What is H N O 3 formula?
H N O 3 is nitric acid.
492. Why is H N O 3 strong?
It fully ionizes in water.
493. What is F e S formula?
F e S is iron(II) sulphide.
494. Why is F e S black?
Due to its composition.
495. What is C u S formula?
C u S is copper(II) sulphide.
496. Why is C u S insoluble?
497. What is P 2 O 5 formula?
P 2 O 5 is phosphorus pentoxide.
498. Why is P 2 O 5 used?
In drying agents.
499. What is N a C l formula?
N a C l is sodium chloride.
500. Why is N a C l salty?
Due to ionic bonding.
501. What is K N O 3 formula?
K N O 3 is potassium nitrate.
502. Why is K N O 3 used?
In fertilizers and explosives.
503. What is C a S O 4 formula?
C a S O 4 is calcium sulphate.
504. Why is C a S O 4 used?
In plaster and cement.
505. What is M g S O 4 formula?
M g S O 4 is magnesium sulphate.
506. Why is M g S O 4 used?
In medicine and agriculture.
507. What is A l C l 3 formula?
A l C l 3 is aluminium chloride.
508. Why is A l C l 3 used?
In catalysts and chemicals.
509. What is C u ( O H ) 2 formula?
C u ( O H ) 2 is copper(II) hydroxide.
510. Why is C u ( O H ) 2 blue?
Due to copper ions.
511. What is F e ( O H ) 2 formula?
F e ( O H ) 2 is iron(II) hydroxide.
512. Why is F e ( O H ) 2 green?
513. What is H 2 S formula?
H 2 S is hydrogen sulphide.
514. Why is H 2 S smelly?
515. What is C 3 H 8 formula?
C 3 H 8 is propane.
516. Why is C 3 H 8 used?
As fuel in heating.
517. What is C 4 H 10 formula?
C 4 H 10 is butane.
518. Why is C 4 H 10 flammable?
519. What is C 2 H 2 formula?
C 2 H 2 is acetylene.
520. Why is C 2 H 2 used?
In welding torches.
521. What is N 2 formula?
N 2 is nitrogen gas.
522. Why is N 2 stable?
It has a triple bond.
523. What is C l 2 formula?
C l 2 is chlorine gas.
524. Why is C l 2 reactive?
It seeks electrons.
525. What is B r 2 formula?
B r 2 is bromine liquid.
526. Why is B r 2 brown?
527. What is I 2 formula?
I 2 is iodine solid.
528. Why is I 2 purple?
Due to its vapour colour.
529. What is P b O formula?
P b O is lead(II) oxide.
530. Why is P b O yellow?
Due to its structure.
531. What is H g O formula?
H g O is mercury(II) oxide.
532. Why is H g O red?
Due to mercury’s oxidation state.
533. What is K I formula?
K I is potassium iodide.
534. Why is K I used?
In iodized salt.
535. What is N a B r formula?
N a B r is sodium bromide.
536. Why is N a B r used?
In medicine and photography.
537. What is A g B r formula?
A g B r is silver bromide.
538. Why is A g B r light-sensitive?
It decomposes in light.
539. What is C a C l 2 formula?
C a C l 2 is calcium chloride.
540. Why is C a C l 2 used?
In drying agents and de-icing.
541. What is K 2 S O 4 formula?
K 2 S O 4 is potassium sulphate.
542. Why is K 2 S O 4 used?
In fertilizers.
543. What is P b S O 4 formula?
P b S O 4 is lead(II) sulphate.
544. Why is P b S O 4 insoluble?
545. What is C u C O 3 formula?
C u C O 3 is copper(II) carbonate.
546. Why is C u C O 3 green?
547. What is M g C O 3 formula?
M g C O 3 is magnesium carbonate.
548. Why is M g C O 3 used?
In antacids and insulators.
549. What is Z n C O 3 formula?
Z n C O 3 is zinc carbonate.
550. Why is Z n C O 3 white?
551. What is N H 4 C l formula?
N H 4 C l is ammonium chloride.
552. Why is N H 4 C l used?
In batteries and fertilizers.
553. What is C a S O 3 formula?
C a S O 3 is calcium sulphite.
554. Why is C a S O 3 used?
In preservatives.
555. What is N a C l O 3 formula?
N a C l O 3 is sodium chlorate.
556. Why is N a C l O 3 used?
In herbicides and bleaching.
557. What is A l 2 ( S O 4 ) 3 formula?
A l 2 ( S O 4 ) 3 is aluminium sulphate.
558. Why is A l 2 ( S O 4 ) 3 used?
In water purification.
559. What is F e 3 O 4 formula?
F e 3 O 4 is magnetite.
560. Why is F e 3 O 4 magnetic?
Due to iron’s properties.
561. What is C u C l 2 formula?
C u C l 2 is copper(II) chloride.
562. Why is C u C l 2 green?
563. What is Z n C l 2 formula?
Z n C l 2 is zinc chloride.
564. Why is Z n C l 2 used?
In soldering and batteries.
565. What is P b ( N O 3 ) 2 formula?
P b ( N O 3 ) 2 is lead(II) nitrate.
566. Why is P b ( N O 3 ) 2 soluble?
Nitrates are water-soluble.
567. What is K 2 C O 3 formula?
K 2 C O 3 is potassium carbonate.
568. Why is K 2 C O 3 used?
In glass and soaps.
569. What is H 2 C O 3 formula?
H 2 C O 3 is carbonic acid.
570. Why is H 2 C O 3 unstable?
It decomposes to C O 2 and H 2 O.
571. What is C a ( N O 3 ) 2 formula?
C a ( N O 3 ) 2 is calcium nitrate.
572. Why is C a ( N O 3 ) 2 used?
573. What is N a 2 S formula?
N a 2 S is sodium sulphide.
574. Why is N a 2 S used?
In dyes and leather.
575. What is A g 2 S formula?
A g 2 S is silver sulphide.
576. Why is A g 2 S black?
577. What is C u ( N O 3 ) 2 formula?
C u ( N O 3 ) 2 is copper(II) nitrate.
578. Why is C u ( N O 3 ) 2 blue?
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