The effect of addion of gypsum to cement is-

1. It reduces the setting time of cement .    

2. The setting time of cement increases.

3. The colour of cement becomes light .          

4. A shining surface is obtained.

Calcium imide on hydrolysis gives gas (B) which on oxidation by bleaching powder gives gas (C). Gas (C) on reaction with magnesium give compound (D) which on hydrolysis gives again gas (B)> Identify (B), (C) and (D).

(1) $N{H}_3,<mspace\; width="1em"></mspace>N_2,<mspace\; width="1em"></mspace>M{g}_3{N}_2$ 

(2) $N_2,<mspace\; width="1em"></mspace>N{H}_3,<mspace\; width="1em"></mspace>MgNH$

(3) $N_2,<mspace\; width="1em"></mspace>N_2{O}_5,<mspace\; width="1em"></mspace>Mg{\left(N{O}_3\right)}_2$ 

(4)$N{H}_3<mspace\; width="1em"></mspace>,N{O}_2,<mspace\; width="1em"></mspace>Mg{\left(N{O}_2\right)}_2<mspace\; width="1em"></mspace>$

Property of all the alkaline earth metals that increases with their atomic number is :

(A) Solubility of their carbonates

(B) Thermal stability of their sulphates

(C) Ionisation energy

(D) Electronegativity

Which of the following acts as an oxidizing as well as a reducing agent?

(1) ${\mathrm{Na}}_2\mathrm{O}$                                     

(2) ${\mathrm{NaO}}_3$

(3) $\mathrm{NaNO}$                                     

(4) ${\mathrm{NaNO}}_2$

A metal [X] heating on nitrogen gas gives [Y]. [Y] on treatment with ${\mathrm{H}}_2\mathrm{O}$ gives a colourless gas which when passed through ${\mathrm{CuSO}}_4$ solution gives a blue colour. [Y] is-

1. $\mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2$                                     

2. ${\mathrm{Mg}}_3{\mathrm{N}}_2$

3. ${\mathrm{NaN}}_3$                                             

4. $\mathrm{MgO}$

The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to:

(1) Ionic nature of lithium fluoride             

(2) High lattice enthalpy

(3) High hydration enthalpy of lithium ion

(4) Low ionisation enthalpy of lithium atom

The correct relation about the density of Na and K is 

1. Na > K                                                     

2. Na = K

3. K > Na                                                     

4. Li > K

In $K^{+}{F}^{-}$ ionic radius of $F^{-}$ is more while atomic radius of $K^{+}$ is –

(1) Less than $F^{-}$

(2) More than $F^{-}$

(3) Equal to $F^{-}$

(4) None of these

Lattice energy is lowest for –

1. LiF                                                       

2. NaCl

3. KBr                                                       

4. CsI

Which of the following halides has the highest melting point-

(A) NaCl                                           

(B) KCl

(C) NaBr                                           

(D) NaF