Reactivity with Air CO2 and Water (Group 1)

Q.

In a reaction

A + B₂ → AB₂

Identify the limiting reagent, if any, in the following reaction mixtures.

(i) 300 atoms of A + 200 molecules of B

(ii) 2 mol A + 3 mol B

(iii) 100 atoms of A + 100 molecules of B

(iv) 5 mol A + 2.5 mol B

(v) 2.5 mol A + 5 mol B

Q.

List the elements that form a basic oxide with oxygen.

Q.

Why does sodium react more vigorously with water than Lithium?

Q. Which of the following statements is true for all the alkali metals ?

1. Their nitrates decompose on heating to give the corresponding nitrites and oxygen
2. Their chlorides are deliquescent and crystallise as hydrates
3. They react with water to form hydroxide and hydrogen
4. They readily react with halogens to form ionic halides, $M^{+}{X}^{-}$

Q.

Which of the following dioxide is amphoteric in nature?

1. CaO

2. SiO₂

3. CO₂

4. SnO₂

Q.

Do all alkaline earth metals react with water?

Q.

A metal which reacts with cold water vigorously producing hydrogen is

1. Gold

2. Tin

3. Sodium

4. Tungsten

Q.

In what ways lithium shows similarities to magnesium in its chemical behaviour?

Q. The secondary valence of metal cocl3.4nh3 if 1l and 1m solution react with 1 molecules of agno3 only is

Q. When a substance $A$ reacts with water, it produces a combustible gas $B$ and a solution of substance $C$ in water. $D$ reacts with this solution $C$ and produces the same gas $B$ on warming. $D$ can also produce gas $B$ on reaction with dilute $H_{2}S{O}_4$. $A$ imparts a deep golden yellow colour to smokeless flame. $A,B,C$ and $D$ respectively are

1. $Na,H_2,NaOH,Zn$
2. $K,H_2,KOH,Al$
3. $Ca{C}_2,C_2{H}_2,Ca(OH{)}_2,Fe$
4. $Ca,H_2,Ca(OH{)}_2,Sn$

Q. Which one of the following doesnot exist ?

1. $Na{O}_2$
2. $Rb{O}_2$
3. $Cs{O}_2$
4. $K{O}_2$

Q.

Calculate the overall complex dissociation equilibrium constant for the Cu(NH₃)₄²⁺ ion, given that β₄ for this complex is 2.1 × 10¹³.

Q.

When heated in air, the alkali metals form various oxides. Mention the oxides formed by Li, Na and K.

Q.

Which metal forms hydrogen gas when react with cold water?

1. $\mathrm{Na}$

2. $\mathrm{Mg}$

3. $\mathrm{Fe}$

4. $\mathrm{Zn}$

Q. Sodium is heated in air at ${350}^{\circ }C$ to form 'X'. 'X' absorbs $C{O}_2$ and forms sodium carbonate and Y. Which of the following is Y?

1. 

2. 

3. 

4. 

Q. Lithium nitrate is heated to give:

1. $N_2$
2. $O_2$
3. $N{O}_2$
4. $L{i}_{2}O$

Q. 8. The no of faraday required to produce one mole of H20 from hydrogen oxygen fuel cell containing aquaeous alkali as electrolyte is 1)1 2)3 3)2 4)4

Q.

Alkali metals react with water vigorously to form hydroxides and dihydrogen. Which of the following alkali metals reacts with water least vigorously?
(a) Li (b) Na (c) K (d) Cs

Q. Which one of the alkali metals forms only the normal oxide $M_{2}O$ on heating in air?

1. Rb

2. Na

3. Li

4. K

Q. A metal on combustion in air vigorously forms a superoxide X . Name the metal.

1. Na
2. Li
3. None of the above
4. Rb

Q.

Which metal is stored under kerosene oil to prevent it from reacting with air?

Q. ${XCl}_2$ is the chloride of metal $X$. State the formula of the sulphate and the hydroxide of the metal $X$ respectively.

1. ${XSO}_3,X({OH)}_3$
2. ${XSO}_3,XOH$
3. ${XSO}_4,X(OH{)}_2$
4. ${XSO}_4,XOH$

Q. An alkali metal $M$ reacts with air and products are hydrolysed. If gas obtained turns red litmus into blue then metal $M$ can be:

1. $Na$
2. $Li$
3. $Al$
4. $K$

Q. The species that do not contain peroxide ions are

1. $N{a}_2{O}_2$
2. $H_2{O}_2$
3. $L{i}_{2}O$
4. $K{O}_2$

Q. Electrovalence of metal atom is maximum in

1. Magnesium oxide
2. Sodium hydride
3. Calcium carbide
4. Aluminium fluoride
   

Q.

Assertion: A piece of sodium metal catches fire when thrown in water.

Reason: Sodium is a very reactive metal.

1. If both assertion and reason are correct and the reason is the correct explanation for assertion.

2. If both assertion and reason are correct but the reason is not the correct explanation for assertion.

3. If the assertion is correct but the reason is incorrect.

4. If the assertion is incorrect but the reason is correct.

Q.

Match the elements given in Column I with the colour they impart to the flame given in Column II.
$\begin{array}{cc}ColumnI& ColumnII\\ A.Cs& 1.Applegreen\\ B.Na& 2.Violet\\ C.K& 3.Brickred\\ D.Ca& 4.Yellow\\ E.Sr& 5.Crimsonred\\ F.Ba& 6.Blue.\end{array}$

Q.

What happens when

(i) sodium metal is dropped in water ?

(ii) sodium metal is heated in free supply of air ?

(iii) sodium peroxide dissolves in water ?

Q.

Write the chemical formulae for the following compounds:

Sodium bicarbonate

Q.

The reaction of sodium is highly exothermic with H₂O. The rate of reaction is lowered by

1. Lowering the temperature

2. Mixing with alcohol

3. Mixing with acetic acid

4. Making an amalgam