## SCIENCE - 2007 class X

12/15/2014 CBSE

Q.1 What is the
name of physical quantity which is equal to

V/I

Ans. Since V/I =R
where R is called the resistance of the conductor. Therefore, the required
physical quantity

is resistance.

Q.2 Write the type
of reactions in the following :

(i) Reaction
between an acid and a base.

(ii) Rusting of
iron.

Ans. (i)
Neutralisation reaction. (ii) Oxidation reaction.

Q.3 Give the names
of the functional groups.

(i) � CHO (ii) C =
O

Ans. (i) Aldehyde
group (ii) Ketone group

Q.4 Write the
function of Iris in the human eye.

Ans. Iris is a
coloured muscular diaphragm that controls the size of the pupil.

Q.5 What is the
S.I. unit of electrical potential ?

Ans. S.I. unit of
electrical potential is Volt.

Q.6 Choose a strong
acid and a strong base from the following :

CH3COOH, NH4OH,
KOH, HCI

Ans.
HCL Strong acid

KOH Strong base

Q.7 What are esters
? Write an equation to show the formation of an ester.

Ans. Esters are
sweet smelling organic compounds. Their function group is R1COOR2, where R1 and R2 are alkyl radicals.

CH3 COOH + C 2H
5OH  H2SO4
-->� CH3
COOC2 H2  +  H2 O

Ethanoic  Ethanol     Ethyl ethanoate

Acid

Q.8 An electric iron has a rating
of 750 W, 220 V. Calculate :

(i) Current passing through it,
and

(ii) its resistance, when in use.x

Ans. P = 750 watt, V = 220 volt.
I = ? r = ?

We know P = VI

\ (i) I
(Current) = 750 /220

= 3.4 ampere

and (ii) V= R/I

R (Resistance)
= 220 /64.7 ohms

=3.4