[1 Mark Question Answer]

Question 11 Mark

Lime water finds application for testing both carbon dioxide $\&$ carbon monoxide gas individually.

Answer

$CO$ carbon$-$monoxide when passed through lime water, does not produce milkiness where as $\ce{CO_2}$ produces milkiness in lime water and hence is used to test $CO$ and $\ce{CO_2}$.

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Question 21 Mark

Carbon monoxide and not carbon dioxide is a highly poisonous gas.

Answer

$CO$ is highly poisonous combines with haemoglobin of $\text{R.B.C.}$ and reduces the oxygen carrying capacity and death results.

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Question 31 Mark

Both $\ce{CO \& SO_2}$ turn lime water milky. Moist potassium permanganate paper, helps in distinguishing the two gases.

Answer

$\ce{SO_2}$ gas moist potassium permanganate paper turns purple to colourless when comes in contact with sulphur dioxide gas where as $\ce{CO_2}$ gas has no effect.

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Question 41 Mark

It is dangerous to stand behind a running engine of a vehicle.

Answer

Running engine of a vehicle produces carbon monoxide which is dangerous for us.

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Question 51 Mark

Diamond $\&$ graphite are allotropic modifications of carbon.

Answer

Both diamond and graphite are carbon element, differ only in physical state and properties. Both on burning form $\ce{CO_2}$ and nothing is left.

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Question 61 Mark

Starting from carbon dioxide how would you obtain $(a)$ A weak acid $(b)$ A fertilizer $(c)$ A highly poisonous gas $(d)$ Black particles of carbon. $[$Give balanced equations for the same$]$

Answer

$(a)$ Carbonic acid from $\ce{CO_2}$ : when $\ce{CO_2}$ is dissolved in water, carbonic acid is formed.
$\ce{CO_2}+ \ce{H_2 O} \longrightarrow \underset{\text { Carbonic acid }}{ \ce{H_2 CO_3}}$
$(b) \ \ce{CO_2}$ reacts with ammonia gas to form urea $($a nitrogenous fertilizers$)$.
$\underset{\text { Ammonia }}{\ce{2 NH _3}}+ \ce{CO _2} \longrightarrow \underset{\text { Urea [fertilizer] }}{\left[ NH _2\right]_2CO }+ \ce{H_2 O}$
$(c) \ \ce{CO_2}$ is reduced to a highly poisonous gas $CO$ by carbon $($coke$)$.
$\ce{CO_2}+ C \longrightarrow \underset{Carbon monoxide gas} {\ce{2CO}}$
$(d)$ Black particles of carbon : Burning magnesium bums in $\ce{CO_2}$ making use of oxygen of $\ce{CO_2}$ producing black carbon particles.
$\ce{2 Mg} + \ce{CO_2} \rightarrow \ce{2 Mgo} + C$

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Question 71 Mark

In the laboratory preparation of carbon dioxide by action of a dilute acid on a metallic carbonate give $- (a)$ A balanced equation for the preparation $(b)$ A reason for $(i)$ use of a washer bottle containing cone. $\ce{H_2 SO_4}$ in the preparation $(ii)$ Not collecting the prepared gas over water $(iii)$ Not using dilute sulphuric acid as a reactant in the preparation.

Answer

$(a)\ce{CaCO_3}+\ce{2 HCl} \rightarrow \ce{CaCl_2}+ \ce{CO_2}+ \ce{H_2O}$
$(b) (i)$ Cone. $\ce{H_2 SO_4}$ used in washer bottle absorbs moisture from the gas.
$(ii)\ce{CO_2}$ is soluble in water and hence is not collected over water.
$(iii)$ Dil. sulphuric acid is not used as reactant. Since $\ce{H_2 SO_4}$ reacts with calcium carbonate forming a coating of insoluble calcium sulphate $\left[ \ce{CaSO_4}\right]$. The reaction slowly comes to a stop.
$\ce{CaCO_3}+ \ce{H_2 SO_4} ($dil.$) \rightarrow \ce{CaSO_4} ($Insoluble$) + \ce{H_2O + CO_2}$

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Question 81 Mark

State how you would convert carbon dioxide to a metallic carbonate using a basic oxide e.g. sodium oxide. $[$Give a balanced equation$]$

Answer

Basic oxide like $\ce{Na_2O}$ by $\ce{CO_2}$ are converted into carbonate.
$\ce{Na_2O} + \ce{CO_2} \rightarrow \ce{Na _2 CO_3}$

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Question 91 Mark

With reference to the structure of the two crystalline allotropes of carbon, state why diamond is inert or unreactive while graphite is comparably more reactive.

Answer

Structure of diamond is compact and hence unreactive. Graphic has open structure and more prone to chemical attack.

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