Tag: chemistry

Questions Related to chemistry

In ayurvedic preparation of swarnabhasma, what purity of golden will be used?

chemistry introduction to analytical chemistry interpreting a balanced chemical reaction percentage yield stoichiometric calculations

  1. $42$ % gold + silver

  2. $91$ % amalgam

  3. $24$ carat

  4. $58.5$% copper

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Correct Option: A
Explanation:

Swarna Bhasma is prepared from Gold. It is used in Ayurvedic treatment of infertility, asthma, tissue wasting, poisoning etc. This medicine should only be taken strictly under medical supervision.

In the given question option A is the correct answer.

One mole of photons is known as one Einstein of radiation. According to Stark-Einstein law of photochemical equivalence, one mole of reactant absorbs one Einstien of energy. For a photochemical reaction, a term called quantum yield is defined as:
Quantum yield $ (\phi) = \dfrac {No. \,of \,moles \,of \,reactant \,converted} {No. \,of \,Einstein \,absorbed} $
The correct statement(s) is/are:

chemistry introduction to analytical chemistry interpreting a balanced chemical reaction percentage yield stoichiometric calculations

  1. for a chain reaction $\phi _{gas} >> \phi _{solution}$

  2. in a photochemical chain reaction $\phi >> 1$

  3. in a photochemical chain reaction $\phi << 1$

  4. for a chain reaction $\phi _{gas} << \phi _{solution}$

Show answer
Correct Option: A,B
Explanation:
$Quantum \ Yield= \cfrac {Number \ of \ moles \ of \ reactant \ converted}{Number \ of \ einstein \ absorbed}$
An einstein of radiation $=$ one mole of photons
For a chain reaction, $\phi _{gas} >> \phi _{solution}$
and ln photochemical chain reaction $\phi >>1$

A sample of $CaC{O _3}$ is $50\% $ pure. On heating $1.12{\text{ }}L$ of $C{O _2}$ (at STP) is obtained. Residue left (assuming non-volatile impurity) is:

chemistry introduction to analytical chemistry interpreting a balanced chemical reaction percentage yield stoichiometric calculations

  1. 7.8 g

  2. 3.8 g

  3. 2.8 g

  4. 8.9 g

Show answer
Correct Option: A
Explanation:

No. of moles of $CO _2$ evolved $=\cfrac{1.12}{22.4}=0.05$ $moles$

$CaCO _3(s)\overset { \Delta }{ \longrightarrow } CaO\downarrow+CO _2\uparrow$
                             $0.05$        $0.05$ $moles$
So, $0.05$ $moles$ of $CaCO _3$ have  reacted.
Mass $=0.05\times 100=5$ $gm=50\%$ of $CaCO _3$ sample
Total weight $=2\times 5$ $gm=10$ $gm$
Residue left by $CaCO _3=5$ $gm$
Residue left by $CaO=56\times 0.05=2.8$ $gm$
Toatl residue $=5+2.8=7.8$ $gm$

When marble chips are treated with $HCl $, which of the following gas is liberated?

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. CO$ _2$

  2. O$ _2$

  3. CO

  4. NO$ _2$

Show answer
Correct Option: A
Explanation:

Reaction:

$\underbrace{CaCO _3} _{(Marble\quad chips)} +2HCl\longrightarrow CaCl _2+CO _2(g) +H _2O(l)$
So, $CO _2$ gas is liberated.

$Ca(HCO _{3}) _{2} + 2HCl \rightarrow $

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. $CaCl _{2} + 2H _{2}O + 2CO _{2}$

  2. $2CaCl _{2} + 2H _{2}O + 2CO _{2}$

  3. $CaCl _{2} + 4H _{2}O + 2CO _{2}$

  4. $CaCl _{2} + 2H _{2}O + 4CO _{2}$

Show answer
Correct Option: A
Explanation:

$Ca(HCO _{3}) _{2} + 2HCl \rightarrow CaCl _{2} + 2H _{2}O + 2CO _{2}$ 

Metal carbonates react with  acids to give salt, carbon dioxide and water.

Acids react with carbonate and bicarbonates to liberate $CO _{2}$.

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. True

  2. False

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Correct Option: A
Explanation:

The metal ion displaces the proton $(H^+)$ from the acid and a salt is formed along with carbonic acid $(H _2CO _3)$

However, $(H _2CO _3)$ is unstable in atmospheric conditions.
$MgCO _3+2HCl\longrightarrow MgCl _2+H _2CO _3$ (Equation $01$)
$H _2CO _3\longrightarrow H _2O+CO _2$ (Equation $02$)
By adding $01$ and $02$
$MgCl _2+2HCl\longrightarrow MgCl _2+H _2O+CO _2$
Similarly,
$Na _2CO _3+H _2SO _4\longrightarrow Na _2SO _4+H _2CO _3$
here, $H _2CO _3$ is split into $H _2O+CO _2$
$ZnCO _3+2HNO _3\longrightarrow Zn(NO _3) _2+H _2O+CO _2$

Metal carbonates react with _______ to give salt, carbon dioxide and water.

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. acids

  2. bases

  3. alkalis

  4. non-metals

Show answer
Correct Option: A
Explanation:

Metal carbonates react with acids to give salt, carbon dioxide and water.
$NaHCO _{3} + 2HCl (dil) \rightarrow NaCl + H _{2}O + CO _{2(g)}$.

Choose the correct option to complete the reaction.
$CaCO _{3}(s) + 2HCl(aq) \rightarrow $

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. $2CaCl _{2}(aq) + H _{2}O(l) + CO _{2}(g)$

  2. $CaCl _{2}(aq) + 3H _{2}O(l) + CO _{2}(g)$

  3. $2CaCl _{2}(aq) + 4H _{2}O(l) + CO _{2}(g)$

  4. $CaCl _{2}(aq) + H _{2}O(l) + CO _{2}(g)$

Show answer
Correct Option: D
Explanation:

$CaCO _{3}(s) + 2HCl(aq) \rightarrow CaCl _{2}(aq) + H _{2}O(l) + CO _{2}(g)$ 

All metal carbonates and hydrogen carbonates react with acids to gives corresponding salt, carbon dioxide and water.

Hydrochloric acid react with carbonate to form:

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. carbide

  2. hydride

  3. chloride

  4. none of the above

Show answer
Correct Option: C
Explanation:

Chloride
Hydrochloric acid reacts with Carbonate to form chlorides.
$2HCl+CaCo _3\rightarrow CaCl _2+H _2O+CO _2$

$2HCl{(aq)} + MgCO _{3}(s)\rightarrow$

chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

  1. $MgCl _{2}(aq) + CO _{2}(g) + H _{2}O(l)$

  2. $MgCl _{2}(aq) + CO _{2}(g)$

  3. $MgCl _{2}(aq) + H _{2}O(l)$

  4. $MgCl _{2}(aq) + CO _{2}(g) + 3H _{2}O(l)$

Show answer
Correct Option: A
Explanation:

$(A)$  $MgCl _{2}(aq)$ + $CO _{2}(g)$ + $H _{2}O(l)$


$Reaction$ : $2HCl(aq)$ + $MgCO _{3}(s)$ $\rightarrow$ $MgCl _{2}(aq)$ + $CO _{2}(g)$ + $H _{2}O(l)$