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CLASS - 10 SCIENCE IMPORTANT QUESTIONS OF MARK 5   FOR BOARD EXAMINATION

QUESTION NO. 11

1. Isomers define.
2. Draw two possible isomers of the compound with molecular formula C3 H6O and write their names.
3. Differentiate East verification and saponification on the basis of chemical equation.

ANSWER NO. 11

1. ISOMERS : 

the compound which have identical molecular formula but different structure are called isomers.
2.


3. ESTERIFICATION REACTION :

  Ester are most commonly formed by reaction of an acid and alcohol. Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst give and ester.

SAPONIFICATION : 

On heating with Sodium Hydroxide, which is an alkali, the step is converted back to alcohol and sodium salt of carboxylic acid. This reaction is known as saponification.

QUESTION NO. 12

What is methane ? Draw it electron dot structure name the type types of bonds formed in this compound fullstop why are such compounds.
(i) poor conductor of electricity question mark
(ii) have low melting and boiling points? What happen when this compound is burnt in oxygen ?

ANSWER NO. 12

METHANE

It is a compound of carbon. Methane is widely used as a fuel and is a measure component of biogas and compressed natural gas.



Carbon compounds which contain only carbon and hydrogen are called hydrogen carbon. Among these, the saturated hydrogen hydrocarbons are called alkanes. The unsaturated hydrocarbon which contains one or more double Ponds are called alkenes. Those containing one or more triple bonds are called alkynes.

(i) since the electrons are shared between atoms and low charged particle are formed such covalent compounds are generally poor conductor of electricity.
(ii) covalently bonded molecules are strong bonds within the molecules, but intermolecular forces are weak. This gives rise to the low melting and boiling point.

Saturated hydrocarbons generally give a clean flame.

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