Tag: chemistry

Questions Related to chemistry

Which of the following is not regarded as a pollutant?

chemistry air environment and pollution environment pollution for a pollution free nature

  1. $NO _{2}$

  2. $CO _{2}$

  3. $SO _{2}$

  4. CO

Show answer
Correct Option: B
Explanation:

Pollutants can be classified as solid, gaseous or liquid pollutants. Also, it can be classified as physical, chemical and biological. They can be further classified as degradable and non-degradable. $NO _2$, $SO _2$  and CO are gases which if present in great quantity in the atmosphere can cause pollution.

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) Biodegradable pollutants (i) DDT
(B) Non-biodegradable pollutants (ii) $SO _{2}$
(C) Primary pollutants (iii) PAN
(D) Secondary pollutants (iv) Sewage
chemistry air environment and pollution environment pollution for a pollution free nature

  1. (A) $\rightarrow$ (iii), (B) $\rightarrow$ (iv), (C) $\rightarrow$ (ii), (D) $\rightarrow$ (i)

  2. (A) $\rightarrow$ (ii), (B) $\rightarrow$ (iii), (C) $\rightarrow$ (iv), (D) $\rightarrow$ (i)

  3. (A) $\rightarrow$ (i), (B) $\rightarrow$ (ii), (C) $\rightarrow$ (iii), (D) $\rightarrow$ (iv)

  4. (A) $\rightarrow$ (iv), (B) $\rightarrow$ (i), (C) $\rightarrow$ (ii), (D) $\rightarrow$ (iii)

Show answer
Correct Option: D
Explanation:

Sewage is a biodegradable pollutant which can be degraded. DDT is a type of non biodegradable pollutant. $ S0 _2 $ is a primary pollutant, affecting the environment. PAN is considered as a secondary pollutants among all the pollutants. 

Match the upper limit concentration of the pollutants given in column I with column II and mark the appropriate choice.

Column I Column II
(A) Lead (i) 500 ppm
(B) Sulphate (ii) 10 ppm
(C) Nitrate (iii) 50 ppb
(D) Fluoride (iv) 50 ppm
chemistry air environment and pollution environment pollution for a pollution free nature

  1. (A) $\rightarrow$ (ii), (B) $\rightarrow$ (iii), (C) $\rightarrow$ (i), (D) $\rightarrow$ (iv)

  2. (A) $\rightarrow$ (iii), (B) $\rightarrow$ (i), (C) $\rightarrow$ (iv), (D) $\rightarrow$ (ii)

  3. (A) $\rightarrow$ (i), (B) $\rightarrow$ (iv), (C) $\rightarrow$ (iii), (D) $\rightarrow$ (ii)

  4. (A) $\rightarrow$ (iv), (B) $\rightarrow$ (ii), (C) $\rightarrow$ (iii), (D) $\rightarrow$ (i)

Show answer
Correct Option: B
Explanation:

The concentration of pollutants like lead is 50 ppb. So the water gets contaminated with lead. The concentration of sulphate is 500 ppm. The concentration of nitrate is 50 ppm. Concentration of fluoride is 10 ppm. 

The pollutants which come directly in the air from sources are called primary pollutants. Primary pollutants. Which of the following belongs to secondary air pollutants? 

chemistry air environment and pollution environment pollution for a pollution free nature

  1. $CO$

  2. $Hydrocarbon$

  3. $Peroxyacetyle\ nitrate\ (PAN)$

  4. $NO$

Show answer
Correct Option: D
Explanation:
The correct answer is NO (nitrogen oxide) which reacts with oxygen to form nitrogen dioxide, participate in a complex of ultraviolet-driven photochemical reactions. and it also forms acid rain when it reacts with water.

$PhCOOH\xrightarrow{DIBALH} $ 

chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

  1. $PhCHO$

  2. $PhO$

  3. $PhCH _2OH$

  4. None of these

Show answer
Correct Option: A
Explanation:

Benzoic acid on reduction with di-isobutyl aluminium hydride (DIBALH) gives benzaldehyde.
$\displaystyle PhCOOH \xrightarrow {DIBALH} PhCHO $
Di-isobutyl aluminium hydride (DIBALH) is a reducing agent. It reduces carboxylic acids to aldehydes.

How  - $COOH$ can be converted into $CH _3$ group?

chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

  1. $\;Na\;&\;alcohol$

  2. $\;Zn+HCl$

  3. $\;LiAlH _4$

  4. $\;Hl\;&\;red\;phosphorous$

Show answer
Correct Option: D
Explanation:

$-COOH$ can be converted into $CH _3$ group by heating with a mixture of HI and red phosphorus.
$CH _3COOH  \xrightarrow {\;Hl\;&\;red\;phosphorous} CH _3-CH _3$

Which of the following reagents can convert acetic acid into ethanol?

chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

  1. $Sn + HCl$

  2. $H _{2} + Pt$

  3. $LiAlH _{4}+$ Ether

  4. $Na +$ Alcohol

Show answer
Correct Option: C
Explanation:

$CH _{3}COOH\xrightarrow[]{LiAlH _{4}}C _{2}H _{5}OH$.
$ LiAlH _{4} $ being a strong reducing agent can reduce acids to alcohols.

Which of the following reduces carboxylic acid directly to primary alcohols?

chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

  1. $LiAlH _{4}$

  2. $Na + C _{2}H _{5}OH$

  3. $\text{Lindlar's Catalyst}$

  4. $H _{2}$

Show answer
Correct Option: A
Explanation:

$LiAlH _{4}$ is a very strong reducing agent. It can reduce acids directly to alcohols.

Which of the following reaction is not the oxidation?

chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

  1. $CH _{3} - CHO \rightarrow CH _{3}COOH$

  2. $C _{2}H _{5}OH \rightarrow CH _{3} - CHO$

  3. $C _{2}H _{5}OH \rightarrow CH _{3} - COOH$

  4. $CH _{3}COOH \rightarrow C _{2}H _{5}OH$

Show answer
Correct Option: D

$RCOOH \rightarrow  RCH _{2}OH$

This mode of reduction of an acid to alcohol can be effected only by

chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

  1. Zn/HCl

  2. Na - alcohol

  3. Aluminium isopropoxide and isopropyl

    alcohol

  4. LiAlH$ _{4}$

Show answer
Correct Option: D
Explanation:

D