English Medium इयत्ता १० - CBSE Important Questions for Science

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

Name the oxidising agent used for the conversion of ethanol to ethanoic acid. Distinguish between ethanol and ethanoic acid on the basis of (i) litmus test, (ii) reaction with sodium carbonate 

Distinguish between homologous organs and analogous organs. In which category would you place wings of a bird and wings of a bat? Justify your answer giving a suitable reason.

List in tabular form three physical and two chemical properties on the basis of which ethanol and ethanoic acid can be differentiated.

Which of the following observations is true about dilute solution of acetic acid?

(A) It smells like vinegar and turns red litmus blue

(B) It smells like onion and turns blue litmus red

(C) It smells like orange and turns red litmus blue

(D) It smells like vinegar and turns blue litmus red

A student takes Na₂CO₃ powder in a test tube and pours some drops of acetic acid over it. He observes:

(A) no reaction in the test tube

(B) colourless gas with pungent smell

(C) bubbles of a colourless and odourless gas

(D) white fumes with smell of vinegar

A student adds 4 mL of acetic acid to a test tube containing 4 mL of distilled water. He then shakes the test tube and leaves it to settle. After about 10 minutes he observes:

(A) a layer of water over the layer of acetic acid

(B) a layer of acetic acid over the layer of water

(C) a precipitate settling at the bottom of the test tube

(D) a clear colourless solution

Write the chemical equation for the following:

Combustion of methane

Assertion (A): Esterification is a process in which a sweet-smelling substance is produced.

Reason (R): When esters react with sodium hydroxide an alcohol and sodium salt of carboxylic acid are obtained.

3 mL of ethanol is taken in a test tube and warmed gently in a water bath. A 5% solution of alkaline potassium permanganate is added to the first drop by drop to this solution, then in excess.

1. How is a 5% solution of KMnO₄ prepared?
2. State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess?
3. Write the chemical equation of this reaction.

Answer the following question.
What is methane?

Answer the following question.
Draw methane electron dot structure.

Answer the following question.
Name the type of bonds formed in the methane compound.

Answer the following question.
Why are methane compounds have poor conductors of electricity?

Answer the following question.
Why are methane compounds have low melting and boiling points?

Answer the following question.
What happens when methane compound burns in oxygen?

Write the chemical equation for the following:

Oxidation of ethanol

"Carbon prefers to share its valence electrons with other atoms of carbon or with atoms of other elements rather than gaining or losing the valence electrons in order to attain noble gas configuration." Give reasons to justify this statement.

Consider the carbon compounds having following molecular formula:

(i) C₃H₆ (ii) C₃H₈ (iii) C₄H₆ (iv) C₆H₆ (v) C₆H₁₂

1. State the number of double covalent bonds present in C₃H₆.
2. Write the formula of first member of the homologous series to which the carbon compound C₄H₆ belongs.
3. Which one of the above compounds forms a ring structure of carbon atoms?
4. Identify, which of the above compounds, is a member of alkane series.

"Two different forms of carbon - diamond and graphite have different structure and very different physical properties even though their chemical properties are same." Explain why.