In replacement reaction 

The reaction will be most favorable if M happens to be:

1.  K
2.  Rb
3.  Li
4.  Na

Match List I with List II for the composition of substances and select the correct answer using the code given below:

Code :

The compound A on heating gives a colourless gas and a residue that is dissolved in water to obtain B. Excess of CO₂ is bubbled through an aqueous solution of B. C is solid. Solid C on gentle heating gives back A. The compound A is:

1. Na₂CO₃

2. K₂CO₃

3. CaSO₄.2H₂O

4. CaCO₃

When a substance A reacts with water it produces a combustible gas B and a solution of substance C in water. When another substance D reacts with this solution of C, it also produces the same gas B on warming but D can produce gas B on reaction with dilute sulphuric acid at room temperature. A imparts a deep golden yellow colour to a smokeless flame of Bunsen burner. 

The substance A, B, C and D, respectively are:
1.  K, $H_2$, NaOH, Zn
2.  Na, NaOH, $H_2$ , Zn
3.  Li, $H_2$, LiOH, Zn
4.  None of the above

A solid compound 'X' on heating gives CO₂ gas and a residue. The residue mixed with water forms 'Y'. On passing an excess of CO₂ through 'Y' in water, a clear solution, 'Z' is obtained. On boiling 'Z', compound 'X' is reformed. The compound 'X' is:

1. ${\mathrm{CaCO}}_3$

2. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

3. ${\mathrm{K}}_2{\mathrm{CO}}_3$

4. $\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2$

The most convenient method to protect the bottom of the ship made of iron is:

1. Coating it with Red lead oxide.
2. White tin plating.
3. Connect it with the Mg block.
4. Connect it with the Pb block.

Among the role of gypsum, CaSO₄.2H₂O in the setting of cement, identify the correct option from the following:

1. It fastens the setting process

2. It provides water molecules for the hydration process

3. It helps to remove water molecules

4. It slows down the setting process

Identify the correct statement from the following:

Alkali metals are not found in nature in their elemental state because they are : 

1. Less reactive due to low ionization energies.

2. Highly reactive due to low ionization energies.

3. Highly reactive due to low electron gain enthalpy.

4. Less reactive due to low electron gain enthalpy.

The oxidation state of sodium in Na₂O₂ is -

1. +1

2. -1

3. 0

4. +2