This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “P-Block Elements – Oxides of Nitrogen”.
1. Dinitrogen oxide is also called laughing gas.
Explanation: Dinitrogen oxide (N2O) or Nitrogen(I) oxide or nitrous oxide is also known as laughing gas. It is called so because of its intoxicating effects when inhaled. It is used in dentistry and surgery for its anaesthetic and analgesic effects.
2. What is the range of the oxidation states shown by nitrogen in its oxides?
a) +1 to +3
b) +2 to +4
c) +1 to +2
d) +1 to +5
Explanation: Nitrogen in the ground state has a valency of 3 in its ground state and it has a valency of 5 in its excited state. Hence, it forms oxides with a wide range of oxidation states where the oxidation states vary from +1 to +5.
3. Which of the following is true about dinitrogen oxide?
a) It is yellow in colour
b) The oxidation state of nitrogen is +5
c) It is basic in nature
d) It is a colourless gas
Explanation: Dinitrogen oxide (N2O) or Nitrogen (I) oxide is an oxide of nitrogen where nitrogen has an oxidation state of +1. It is a colourless gas which is neutral in nature and which has a sweet odour.
4. Nitrogen monoxide reacts with oxygen to form nitrogen dioxide.
Explanation: Nitrogen monoxide or Nitrogen(II) oxide or nitric oxide is a very reactive compound due to the presence of an odd electron(paramagnetic nature). It instantly reacts with oxygen to form nitrogen dioxide.
5. What does dinitrogen oxide on reaction with sodamide produce?
a) Nitrogen gas
b) Nitric acid
c) Nitrogen dioxide
d) Sodium azide
Explanation: Dinitrogen oxide (N2O) or Nitrogen(I) oxide, commonly called laughing gas, reacts with liquid sodamide or sodium amide (NaNH2) at a temperature of 473K in order to produce sodium azide (NaN3) and water.
6. What temperature does dinitrogen oxide dissociate at?
Explanation: At a temperature of about 873K, dinitrogen oxide gas dissociates. Two molecules of dinitrogen oxide gas (N2O) dissociate to form oxygen gas (O2) and nitrogen gas (N2) in the ratio 1:2 respectively.
7. What is the IUPAC name of NOCl?
a) Nitrogen monoxy chloride
b) Chloroxy nitrogen
c) Nitroxy chlorine
d) Nitrosyl chloride
Explanation: Nitrosylchloride is the IUPAC name with the formula (NOCl). It is a yellow coloured gas which is a strong oxidizing agent. Nitrogen monoxide reacts with chlorine in order to form nitrosyl chloride.
8. Which of the following is not an alternative name of dinitrogen trioxide?
a) Nitrogen sesquioxide
b) Nitrogen (III) oxide
c) Anhydride of nitrous acid
d) Nitrogen peroxide
Explanation: Dinitrogen trioxide is an oxide of nitrogen which can also be called as nitrogen sesquioxide, nitrogen (III) oxide or anhydride of nitrous acid. Nitrogen dioxide is also known as nitrogen peroxide.
9. What colour does the compound dinitrogen trioxide appear in its liquid state?
a) It is colourless
Explanation: Dinitrogen trioxide (N2O3) is found to be blue in colour in both its liquid and solid state. The blue colouration tends to appear because dinitrogen trioxide is a radical pair of nitric oxide and nitrogen dioxide that tend to absorb strongly in the visible region to appear bright blue.
10. Which of the following compounds can be identified as nitryl fluoride?
Explanation: Nitrogen dioxide (NO2), also known as nitrogen peroxide or nitrogen (IV) oxide, is paramagnetic in nature. So, it reacts with fluorine (F2) and chlorine (Cl2) forming their respective nitryl compounds. The chemical representation of nitryl fluoride is NO2F.
11. Which of the following oxide can act as both reducing and oxidising agent?
a) Dinitrogen oxide
b) Nitric oxide
c) Nitrogen dioxide
d) Dinitrogen pentoxide
Explanation: Nitric oxide acts as both an oxidising agent and a reducing agent whereas all the other oxides of nitrogen act as oxidising agents only. The oxidising nature of nitric acid can be observed in its reaction with hydrogen sulphide while its reducing nature can be observed in its reaction with acidified potassium permanganate.
12. Which of the following oxides of nitrogen is a neurotransmitter?
Explanation: Although nitric acid (NO) is very reactive and harmful, it occurs in small traces in biological systems. It acts as a neurotransmitter and helps in controlling blood pressure by relaxing blood vessels.
13. What are the complexes formed by nitric oxide with transition metals called?
Explanation: Nitric oxide (NO) readily forms complexes with transition metals. These complexes are called nitrosyls. Two important nitrosyl complexes are sodium nitroprusside and the nitroprusside anion.
14. Which of the following statements is incorrect regarding dinitrogen pentoxide?
a) It is basic in nature
b) It is also known as the anhydride of nitric acid
c) It exists as a colourless solid below 273K
d) The oxidation state of nitrogen is +5
Explanation: Dinitrogen pentoxide (N2O5), also known as nitrogen (V) oxide or anhydride of nitric acid, is an oxide of nitrogen which is acidic in nature. The oxidation state of nitrogen in it is +5. It exists as a solid below 273K and decomposes to form nitrogen dioxide, nitric oxide and oxygen above a temperature of 273K.
15. What is the bond angle between the oxygen atoms in nitrogen dioxide?
Explanation: Ideally, according to its structure, the bond angle between the two oxygen atoms in nitrogen dioxide should be 120°. But, the one lone electron on the nitrogen atom exerts a less repulsion than normal on the two oxygen atoms. So, they spread out more, to form a bond angle of 134°.
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