Carbon and Its Compounds

Why is candle flame generally yellow?

Give a chemical test to distinguish between:

(i) Ethane and ethene

(ii) Ethanol and ethanoic acid

(iii) Soaps and detergents.

Read the following and answer any four questions from (i) to (v).

A hydrocarbon (P) has the molecular formula C₁₀H₂₂ hydrocarbon (Q) has two carbon atoms less than (P) and belong to the same homologous series. A hydrocarbon (R) has two carbon atoms more than (P) and belong to the same homologous series.

(i) What is the molecular formula of (Q)?

1. C₁₂H₂₆
2. C₈H₁₆
3. C₈H₁₈
4. C₈H₁₄

(ii) To which homologous series do the compound (P), (Q) and (R) belong?

1. C_nH_2n
2. C₂H_2n-2
3. C_nH_2n+2
4. C_nH_2n+1

(iii) What is the molecular formula of (R)?

1. C₁₂H₂₆
2. C₁₂H₂₄
3. C₁₂H₂₂
4. C₁₂H₂₈

(iv) Identify the correct statement about compounds (P), (Q) and (R).

1. They have same melting and boiling points.
2. They have same chemical properties.
3. They have different general formula.
4. They differ by -CH unit.

(v) Compounds (P), (Q) and (R) are:

1. Alkanes. b. Alkenes.
2. Alkynes. d. None of these.

Read the following and answer any four questions from (i) to (v).

The table given below shows six organic compounds A, B, C, D, E and F having different molecular formula:

(i) Which of the following compounds belong to same homologous series?

1. E and F
2. B and C
3. A and B
4. C and D

(ii) Which of the following is the member of the same homologous series as E?

1. D
2. A
3. F
4. B

(iii) Identify the correct statements.

1. A and F are saturated hydrocarbons while all others are unsaturated hydrocarbons.
2. C and D belong to a homologous series having general formula C_nH_2n.
3. B and E are alkynes.
4. All the compounds have same physical and chemical properties.

(iv) Compound B is:

1. An alkane.
2. An alkene.
3. An alkyne.
4. None of these.

(v) Compound (F) has a general formula:

1. C_nH_2n-2
2. C_nH_2n
3. C_nH_2n+4
4. C_nH_2n+2

For question two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

1. Both A and R are true, and R is correct explanation of the assertion.
2. Both A and R are true, but R is not the correct explanation of the assertion.
3. A is true, but R is false.
4. A is false, but R is true.

Assertion: Olefins have the general formula C_nH_2n+1.

Reason: There is at least one double bond between two carbon atoms in their molecules.

For question two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

1. Both A and R are true, and R is correct explanation of the assertion.
2. Both A and R are true, but R is not the correct explanation of the assertion.
3. A is true, but R is false.
4. A is false, but R is true.

Assertion: Diamond and graphite do not have the same crystalline structure.

Reason: Diamond is crystalline while graphite is amorphous.

What are the essential constituents of all organic compounds?