The furring of kettles is caused by the presence of what compound in water?
calcium tetraoxosulphate (IV)
calcium hydrogentrioxocarbonate (IV)
calcium hydroxide
calcium trioxocarbonate (IV)
Correct answer is D
Calcium hydrogen carbonate, often present in temporary hard water, is boiled in a kettle to remove the hardness. In the process, a scale forms on the inside of the kettle in a process known as furring of kettles. This scale is composed of calcium carbonate.
NH3(g) + HCl(s) → NH 4Cl (s)
The entropy change in the system above is
positive
zero
negative
intermediate
Correct answer is C
Entropy s is a measure of the degree of disorder or randomness of a substance. The entropy charge in the system is negative. Options B, C, D will not give negative but the result into positive
What volume of 0.5mldm3 H2SO4 will exactly neutralize 20cm3 of 0.1moldm3 NaOH Solution?
2.0cm3
5.0cm3
6.8cm3
8.3cm3
Correct answer is A
2NaOH + H2SO4 → Na2SO4 + 2H2O
CaVa) ÷ (CbVb) = ratio of acid / ratio of base
0.5Va ÷ (0.1 × 20) = ½
Va = 2.0cm3
I, II and III
I and II only
III only
I only
Correct answer is D
Only primary alkanols undergo oxidation to produce alkanoic acid. Option A,B,C will not produce alkanoic acid
Hydrogen can be displaced from a hot alkaline solution by
Fe
Cu
Ca
Sn
Correct answer is D
Tin dissolves in concentrated solution of alkalis to give trioxostannate(IV) salt and hydrogen.