When a standard solution of NaOH is left in air for a few hours :

(1) a precipitate will form

(2) strength of solution will decrease

(3) the strength of solution will increase

(4) the concentration of $N{a}^{+}.$ion in solution will remains same

${\mathrm{CaCl}}_2$ is preferred over NaCl for clearing ice on roads particularly in very cold countries. This is because:

1. ${\mathrm{CaCl}}_2$ is less soluble in ${\mathrm{H}}_2\mathrm{O}$ than NaCl.

2. $CaC{l}_2$ is hygroscopic but NaCl is not.

3. Eutectic mixture of ${\mathrm{CaCl}}_2/{\mathrm{H}}_2\mathrm{O}$ freezes at $-55°C$ while that of $\mathrm{NaCl}/{\mathrm{H}}_2\mathrm{O}$ freezes at $-18°C$.

4. NaCl makes the road slippery but ${\mathrm{CaCl}}_2$ does not.

Which metal bicarbonates does not exist in solid state?

(i) $LiHC{O}_3$       (ii) $Ca{\left(HC{O}_3\right)}_2$     (iii) $Zn{\left(HC{O}_3\right)}_2$      (iv)$AgHC{O}_3$

(1) i,ii,iii,iv                           

(2) i,ii,iii

(3) i,ii,iv                               

(4) ii,iii,iv

The incorrect statement among the following is-

1. The milk of magnesia used as an antacid is chemically $\mathrm{MgO} + {\mathrm{MgCl}}_2$

2. Stability of alkali metal peroxides increases with an increase in atomic number.

3. Hydration energy of AgF is higher than its lattice energy.

4. Anhydrous ${\mathrm{MgCl}}_2$ cannot be prepared by direct heating of ${\mathrm{MgCl}}_2 . 6{\mathrm{H}}_2\mathrm{O}$. 

Which of the following order is correct?

1. $K^{+}<C{a}^{2+}<p^{3-}<S^{2-}$: Ionic size

2. $N{a}_{\left(aq.\right)}^{+}>K_{\left(aq.\right)}^{+}>R{b}_{\left(aq.\right)}^{+}>C{s}_{\left(aq.\right)}^{+}$: Electrical conductance

3. $A{l}_{\left(aq.\right)}^{3+}>M{g}_{\left(aq.\right)}^{2+}>N{a}_{\left(aq.\right)}^{+}$: Hydrated size

4. $I_{\left(aq.\right)}^{-}<B{r}_{\left(aq.\right)}^{-}<C{l}_{\left(aq.\right)}^{-}<F_{\left(aq.\right)}^{-}$: Ionic mobility

Give the correct order of initials T or F for following statements. Use T if statement is true and F if it is false.

$\left(\mathrm{I}\right) \mathrm{Numbers} \mathrm{of} \mathrm{S}—\mathrm{S} \mathrm{bonds} \mathrm{in} {\mathrm{H}}_2{\mathrm{S}}_{\mathrm{n}}{\mathrm{O}}_6 \mathrm{are} (\mathrm{n}+1)$
$\left(\mathrm{II}\right) \mathrm{When} {\mathrm{F}}_2 \mathrm{reacts} \mathrm{with} \mathrm{water} \mathrm{gives} \mathrm{HF}, {\mathrm{O}}_2 \mathrm{and} {\mathrm{O}}_3$
$\left(\mathrm{III}\right) {\mathrm{LiNO}}_3 \mathrm{and} {\mathrm{BaCl}}_2 \mathrm{compounds} \mathrm{are} \mathrm{used} \mathrm{in} \mathrm{fire} \mathrm{works}$
$\left(\mathrm{IV}\right) \mathrm{Be} \mathrm{and} \mathrm{Mg} \mathrm{are} \mathrm{ionic} \mathrm{and} \mathrm{polymeric}$
$$
$\left(\mathrm{a}\right)\hspace{0.17em}\mathrm{FTTF} \left(\mathrm{b}\right) \mathrm{FTTT} \left(\mathrm{c}\right) \mathrm{TFTT} \left(\mathrm{d}\right) \mathrm{TTFF}$

Which is not correctly matched?

(1) Basic strength of oxides                                 ${\mathrm{Cs}}_2\mathrm{O}<{\mathrm{Rb}}_2\mathrm{O}<{\mathrm{K}}_2\mathrm{O}<{\mathrm{Na}}_2\mathrm{O}<{\mathrm{LiO}}_2$

(2) Stability of peroxides                                      ${\mathrm{Na}}_2\mathrm{O} <{\mathrm{K}}_2{\mathrm{O}}_2<{\mathrm{Rb}}_2{\mathrm{O}}_2<{\mathrm{Cs}}_2{\mathrm{O}}_2$

(3) Stability of bicarbonate                                   ${\mathrm{LiHCO}}_3<{\mathrm{NaHCO}}_3<{\mathrm{KHCO}}_3<{\mathrm{RbHCO}}_3<\mathrm{Cs} {\mathrm{HCO}}_3$

(4) Melting Point                                                  $\mathrm{NaF}<\mathrm{NaCl}<\mathrm{NaBr}<\mathrm{Nal}$

(A) 1 and 4                                           

(B) 1 and 3

(C) 1 and 2                                           

(D) 2 and 3

Which of the following reactions of potassium superoxide supply oxygen gas in the breathing equipments used in space and submarines?

(1) Reaction of superoxide with nitrogen in the exhaled air.

(2) Reaction of superoxide with moisture in the exhaled air.

(3) Reaction of superoxide with carbon dioxide in the exhaled air

(1) (1), (2) and (3)                                       

(2) (2) and (3) only

(3) (2) only                                                 

(4) (1) and (2) only

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) ${\mathrm{NaNO}}_2$

Alkaline earth metal nitrates on heating decompose to give:

(1) $\mathrm{M}{\left({\mathrm{NO}}_2\right)}_2 \mathrm{and} {\mathrm{O}}_2 \mathrm{only}$                                   

(2) $\mathrm{MO}, {\mathrm{N}}_2 \mathrm{and} {\mathrm{O}}_2$

(3) $\mathrm{MO}, {\mathrm{NO}}_2 \mathrm{and} {\mathrm{O}}_2$                                         

(4) $\mathrm{MO} \mathrm{and} {\mathrm{NO}}_2 \mathrm{only}$