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PRACTICAL CHEMISTRY

37278 Which BLUE LIQUID is obtained on reacting equimolar amounts of two gases at $30^{o} C$ ?

1

N_{2} O

2

N_{2} O_{3}

3

N_{2} O_{4}

4

N_{2} O_{5}

Explanation:

(b) ${N O}_{(g)}$ + ${N O_{2}}_{(g)}$ $\overset{- 30^{\circ} C}{\to}$ ${N_{2} O_{3}}_{(l)}$
(BLUE)

PRACTICAL CHEMISTRY

37279 $M n O_{2}$ and $H_{2} S O_{4}$ added to $N a C l$ , the greenish yellow gas liberated is

1

C l_{2}

2

N H_{3}

3

N_{2}

4

H_{2}

Explanation:

(a)Yellowish-green gas of chlorine with sufocating odour is evolved when the solid chloride mixed with manganese dioxide is heated with concentrated $H_{2} S O_{4}$ .
$N a C l + H_{2} S O_{4} \to N a H S O_{4} + H C l$
$M n O_{2} + 4 H C l \to M n C l_{2} + 2 H_{2} O + C l_{2}$

PRACTICAL CHEMISTRY

37280 Which of the following statement(s) is(are) correct when a mixture of $N a C l$ and $K_{2} C r_{2} O_{7}$ is gently warmed with conc. $H_{2} S O_{4}$

1 A deep red vapour is evolved

2 The vapour when passed into

N a O H

solution gives a yellow solution of

N a_{2} C r O_{4}

3 Chromyl chloride is formed

4 All of the above

Explanation:

(d) Chromyl chloride test
$4 N a C l + K_{2} C r_{2} O_{7} + 3 H_{2} S O_{4} \overset{heat}{\to}$ $K_{2} S O_{4} + 2 N a_{2} S O_{4} + \underset{chromyl chloride (orange red)}{2 C r O_{2} C l_{2} + 3 H_{2} O}$
$4 N a O H + C r O_{2} C l_{2} \to \underset{Sod . chromate (Yellow)}{2 N a C l + N a_{2} C r O_{4} + 2 H_{2} O}$
$N a_{2} C r O_{4} + {(C H_{3} C O O)}_{2} P b \to 2 C H_{3} C O O N a +$ $\underset{\begin{matrix} Lead chromate \\ (yellow ppt .) \end{matrix}}{P b C r O_{4} ↓}$

PRACTICAL CHEMISTRY

37281 Starch can be used as an indicator for the detection of traces of

1 Glucose in aqueous solution

2 Proteins in blood

3 Iodine in aqueous solution

4 Urea in blood

Explanation:

(c) Starch is colourless but
$S t a r c h + \underset{(v i o l e t)}{I o d i n e} \to \underset{(b l u e - b l a c k)}{S t a r c h I o d i n e}$

PRACTICAL CHEMISTRY

37278 Which BLUE LIQUID is obtained on reacting equimolar amounts of two gases at $30^{o} C$ ?

1

N_{2} O

2

N_{2} O_{3}

3

N_{2} O_{4}

4

N_{2} O_{5}

Explanation:

(b) ${N O}_{(g)}$ + ${N O_{2}}_{(g)}$ $\overset{- 30^{\circ} C}{\to}$ ${N_{2} O_{3}}_{(l)}$
(BLUE)

PRACTICAL CHEMISTRY

37279 $M n O_{2}$ and $H_{2} S O_{4}$ added to $N a C l$ , the greenish yellow gas liberated is

1

C l_{2}

2

N H_{3}

3

N_{2}

4

H_{2}

Explanation:

(a)Yellowish-green gas of chlorine with sufocating odour is evolved when the solid chloride mixed with manganese dioxide is heated with concentrated $H_{2} S O_{4}$ .
$N a C l + H_{2} S O_{4} \to N a H S O_{4} + H C l$
$M n O_{2} + 4 H C l \to M n C l_{2} + 2 H_{2} O + C l_{2}$

PRACTICAL CHEMISTRY

37280 Which of the following statement(s) is(are) correct when a mixture of $N a C l$ and $K_{2} C r_{2} O_{7}$ is gently warmed with conc. $H_{2} S O_{4}$

1 A deep red vapour is evolved

2 The vapour when passed into

N a O H

solution gives a yellow solution of

N a_{2} C r O_{4}

3 Chromyl chloride is formed

4 All of the above

Explanation:

(d) Chromyl chloride test
$4 N a C l + K_{2} C r_{2} O_{7} + 3 H_{2} S O_{4} \overset{heat}{\to}$ $K_{2} S O_{4} + 2 N a_{2} S O_{4} + \underset{chromyl chloride (orange red)}{2 C r O_{2} C l_{2} + 3 H_{2} O}$
$4 N a O H + C r O_{2} C l_{2} \to \underset{Sod . chromate (Yellow)}{2 N a C l + N a_{2} C r O_{4} + 2 H_{2} O}$
$N a_{2} C r O_{4} + {(C H_{3} C O O)}_{2} P b \to 2 C H_{3} C O O N a +$ $\underset{\begin{matrix} Lead chromate \\ (yellow ppt .) \end{matrix}}{P b C r O_{4} ↓}$

PRACTICAL CHEMISTRY

37281 Starch can be used as an indicator for the detection of traces of

1 Glucose in aqueous solution

2 Proteins in blood

3 Iodine in aqueous solution

4 Urea in blood

Explanation:

(c) Starch is colourless but
$S t a r c h + \underset{(v i o l e t)}{I o d i n e} \to \underset{(b l u e - b l a c k)}{S t a r c h I o d i n e}$

PRACTICAL CHEMISTRY

37278 Which BLUE LIQUID is obtained on reacting equimolar amounts of two gases at $30^{o} C$ ?

1

N_{2} O

2

N_{2} O_{3}

3

N_{2} O_{4}

4

N_{2} O_{5}

Explanation:

(b) ${N O}_{(g)}$ + ${N O_{2}}_{(g)}$ $\overset{- 30^{\circ} C}{\to}$ ${N_{2} O_{3}}_{(l)}$
(BLUE)

PRACTICAL CHEMISTRY

37279 $M n O_{2}$ and $H_{2} S O_{4}$ added to $N a C l$ , the greenish yellow gas liberated is

1

C l_{2}

2

N H_{3}

3

N_{2}

4

H_{2}

Explanation:

(a)Yellowish-green gas of chlorine with sufocating odour is evolved when the solid chloride mixed with manganese dioxide is heated with concentrated $H_{2} S O_{4}$ .
$N a C l + H_{2} S O_{4} \to N a H S O_{4} + H C l$
$M n O_{2} + 4 H C l \to M n C l_{2} + 2 H_{2} O + C l_{2}$

PRACTICAL CHEMISTRY

37280 Which of the following statement(s) is(are) correct when a mixture of $N a C l$ and $K_{2} C r_{2} O_{7}$ is gently warmed with conc. $H_{2} S O_{4}$

1 A deep red vapour is evolved

2 The vapour when passed into

N a O H

solution gives a yellow solution of

N a_{2} C r O_{4}

3 Chromyl chloride is formed

4 All of the above

Explanation:

(d) Chromyl chloride test
$4 N a C l + K_{2} C r_{2} O_{7} + 3 H_{2} S O_{4} \overset{heat}{\to}$ $K_{2} S O_{4} + 2 N a_{2} S O_{4} + \underset{chromyl chloride (orange red)}{2 C r O_{2} C l_{2} + 3 H_{2} O}$
$4 N a O H + C r O_{2} C l_{2} \to \underset{Sod . chromate (Yellow)}{2 N a C l + N a_{2} C r O_{4} + 2 H_{2} O}$
$N a_{2} C r O_{4} + {(C H_{3} C O O)}_{2} P b \to 2 C H_{3} C O O N a +$ $\underset{\begin{matrix} Lead chromate \\ (yellow ppt .) \end{matrix}}{P b C r O_{4} ↓}$

PRACTICAL CHEMISTRY

37281 Starch can be used as an indicator for the detection of traces of

1 Glucose in aqueous solution

2 Proteins in blood

3 Iodine in aqueous solution

4 Urea in blood

Explanation:

(c) Starch is colourless but
$S t a r c h + \underset{(v i o l e t)}{I o d i n e} \to \underset{(b l u e - b l a c k)}{S t a r c h I o d i n e}$

PRACTICAL CHEMISTRY

37278 Which BLUE LIQUID is obtained on reacting equimolar amounts of two gases at $30^{o} C$ ?

1

N_{2} O

2

N_{2} O_{3}

3

N_{2} O_{4}

4

N_{2} O_{5}

Explanation:

(b) ${N O}_{(g)}$ + ${N O_{2}}_{(g)}$ $\overset{- 30^{\circ} C}{\to}$ ${N_{2} O_{3}}_{(l)}$
(BLUE)

PRACTICAL CHEMISTRY

37279 $M n O_{2}$ and $H_{2} S O_{4}$ added to $N a C l$ , the greenish yellow gas liberated is

1

C l_{2}

2

N H_{3}

3

N_{2}

4

H_{2}

Explanation:

(a)Yellowish-green gas of chlorine with sufocating odour is evolved when the solid chloride mixed with manganese dioxide is heated with concentrated $H_{2} S O_{4}$ .
$N a C l + H_{2} S O_{4} \to N a H S O_{4} + H C l$
$M n O_{2} + 4 H C l \to M n C l_{2} + 2 H_{2} O + C l_{2}$

PRACTICAL CHEMISTRY

37280 Which of the following statement(s) is(are) correct when a mixture of $N a C l$ and $K_{2} C r_{2} O_{7}$ is gently warmed with conc. $H_{2} S O_{4}$

1 A deep red vapour is evolved

2 The vapour when passed into

N a O H

solution gives a yellow solution of

N a_{2} C r O_{4}

3 Chromyl chloride is formed

4 All of the above

Explanation:

(d) Chromyl chloride test
$4 N a C l + K_{2} C r_{2} O_{7} + 3 H_{2} S O_{4} \overset{heat}{\to}$ $K_{2} S O_{4} + 2 N a_{2} S O_{4} + \underset{chromyl chloride (orange red)}{2 C r O_{2} C l_{2} + 3 H_{2} O}$
$4 N a O H + C r O_{2} C l_{2} \to \underset{Sod . chromate (Yellow)}{2 N a C l + N a_{2} C r O_{4} + 2 H_{2} O}$
$N a_{2} C r O_{4} + {(C H_{3} C O O)}_{2} P b \to 2 C H_{3} C O O N a +$ $\underset{\begin{matrix} Lead chromate \\ (yellow ppt .) \end{matrix}}{P b C r O_{4} ↓}$

PRACTICAL CHEMISTRY

37281 Starch can be used as an indicator for the detection of traces of

1 Glucose in aqueous solution

2 Proteins in blood

3 Iodine in aqueous solution

4 Urea in blood

Explanation:

(c) Starch is colourless but
$S t a r c h + \underset{(v i o l e t)}{I o d i n e} \to \underset{(b l u e - b l a c k)}{S t a r c h I o d i n e}$