CBSE Guess > Papers > Question Papers > Class X > 2008 >Science > Science Theory

Q.14. (a) Name the compound CH₃CH₂OH and identify its functional group.
(b) Give a chemical test to distinguish between ethanol and ethanoic acid.
(c) Name the product formed when an organic acid reacts with an alcohol in the presence of an acid catalyst. What is the name assigned to this type of reaction?

Ans. (a) CH₃CH₂OH → Ethanol
Functional group → alcohol (– OH)
(b) When a small piece of sodium metal is put into ethanol in a dry test tube, rapid effervescence due to the evolution of hydrogen gas isproduced. (When a burning splinter is brought near the mouth of the test tube, the gas burns with a pop sound, which is a characteristic of hydrogen gas).

2CH₃CH₂OH + 2Na → 2CH₃CH₂ONa + H₂

When about 0.5 g of sodium carbonate is added to about 2 ml. of dilute ethanoic acid then carbon dioxide gas with brisk effervescence is produced. (When gas is passed through lime water, lime water turns milky which is a characteristic of carbon dioxide gas).

2CH₃COOH + Na₂CO₃ → 2CH₃COONa + CO₂ + H₂O

(c) When an organic acid reacts with an alcohol in the presence of an acid catalyst, a sweet smelling ester will be formed.

Q. 15. (a) Describe an activity to demonstrate the pattern of magnetic field lines around a straight conductor carrying current.
(b) State the rule to find the direction of magnetic field associated with a current carrying conductor.
(c) Two room heaters are marked 220 V, 500 W and 220 V, 800 W respectively. If the heaters are connected in parallel to 220 V mains supply, calculate :
(i) the current drawn by each heater.
(ii) the resistance of each heater.
(iii) total electric energy consumed in commercial units if they operate simultaneously for 2 hours.

Ans. (a) Activity to demonstrate the pattern of magnetic field lines around a straight conductor carrying current :-

• A straight vertical wire AB passes through a cardboard sheet C.
• The ends of the wire AB are connected to a battery through switch.
• When current is passed through wire AB, it produces a magnetic field around it.
• This magnetic field has magnetic field lines around the wire AB which can be shown by sprinkling iron filings on the cardboard C.
• The iron filings get magnetised. And on tapping the cardboard sheet, the iron filings arrange themselves in circles around the wire showing that the magnetic field lines are circular in nature.

Science 2008 Question Papers Class X
Delhi		Outside Delhi		Compartment Delhi		Compartment Outside Delhi
	All Sets (PDF)				Set 1		Set 1
					Set 2		Set 2
					Set 3		Set 3