Which of the following gases is the most dangerous pollutant?
Hydrogen sulphide
Carbon (lV) oxide
Sulphur (lV) oxide
Carbon (ll) oxide
Correct answer is D
Carbon monoxide is a colourless, odourless and tasteless gas that is produced by the incomplete combustion of fossil fuel. It is the most dangerous of all the pollutant gases and can cause death in very high concentrations.
1
3
5
7
Correct answer is D
MgSO4. YH2O
120g (MgSo4) contains - 18g (water)
20g contain (41 - 20g) water.
120g → 18 y; 20 → 21
∴ 18 y = (126)/(18) = 7
31%
27%
21%
19%
Correct answer is C
Volume of O2 used = 200 - 158 = 42 cm3
% of O2 = (42)/(200) x 100% = 21%
12s
14s
21s
30s
Correct answer is C
(R)o/(R)a √(M)a/(MO (30/7)/(60/t) = √ (35.5)/(16)
(60/t) (30/7)/ √(35.5)/(16) t = (60/30)/(7) x (4)√35.5
t = (60 x 7 x √35.5)/(30 x 4) = 21s
16.0
16.2
17.0
18.0
Correct answer is B
816O, 818O
90% 10%
R.A.M = (90)/(100) x 16 + (10)/(100) x 18 = 14.4 + 1.8 = 16.2