What is the percentage by mass of oxygen in Al2(SO4)3. 2H2O?
[Al = 27, S = 32, H = 1, O = 16]
14.29%
25.39%
50.79%
59.25%
Correct answer is D
Al2(SO4)3. 2H2O
2 * 27 + 3*32 + 14 * 16 + 4 * 1 =
54 + 96 + 224 + 4 = 378
% O2 = (224/378) * (100/1) = 59.25%
Which of the following is physical change?
Burning kerosene
Freezing ice cream
Exposing white phosphorus
Dissolving calcium in water
Correct answer is B
No explanation has been provided for this answer.
22.4 dm3
33.6 dm3
44.8 dm3
67.2 dm3
Correct answer is D
2KClO3 → 2KCl + 3O2
3 moles of oxygen is produced
1 moles of oxygen is 22.4 dm3
3 moles of oxygen is 67.2 dm3
0.44 atmosphere
0.22 atmosphere
0.55 atmosphere
0.33 atmosphere
Correct answer is D
No explanation has been provided for this answer.
146C → X + B
X in the equation above represents
126C
125B
147N
136C
Correct answer is C
146C → X + B
→ X + 0-1e
→ 147X