A major process involved in the softening of hard water is the?
conversion of a soluble calcium salt to its trioxoncarbonate (lV)
decomposition of calcium trioxocarbonate (lV)
conversion of an insoluble calcium salts to its trioxocarbonate (lV)
oxidation of calcium atoms to its ions
Correct answer is A
Now in permanent hardness of water, when washing soda is treated with water, the carbonate ions from sodium carbonate react with calcium and magnesium ions in water and produce an insoluble product.
Therefore, calcium carbonate is precipitated out.
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