IJSO Solution 16-10-10

ISJO QUESTION WITHANSWER (16-10-10)

1.

The diagonals of a rhombus are 12 and 24. The radius of the circle inscribed in the rhombus, is 12

(A*)

5 6

(B)

5

(C) 6 5 (D) not possible as a circle in a rhombus can not be inscribed Sol.

D

C

6 A

12 B

65 AB =

6 2  12 2 = 6 5 Let h is the height of rhombus

Area of Rhombus =

1 × 12 × 24 2

1 × 12 × 24 = 6 5 ×h 2 h=

12  24 1 × 6 5 2

h = 2r =

r= 5.

24 5

12 5

The focal length of a concave mirror is f and the distance from the object to the principal focus is a. The magnitude of magnification obtained will be : (A) (f + a)/f

Sol.

(B*) f /a

Focal length of concave mirror =  – f  Distance of object from principal focus = a So distance of object from pole, u =  –(f + a) 

 –

1 1 1 =  f v u

1 1 1 1 1 1      f v f a v f a f

1 f f a  f ( f  a)  v v f ( f  a) a 

magnification, m =  –

v u

  f ( f  a)  m =  –   m =  – f/a   a( f  a )  magnitude of magnification , m = f/a

(C)

f  /  a

(D) f2 /a2

3.

The type of bond present in CCl4 is : (A) Ionic bond.

(B*) Covalent bond.

(C) Electr Electrova ovalen lentt bon bond. d. (D) Dative Dative bon bond. d. Sol.

CCl4 is made of one carbon atom and 4 chlorine atoms.The carbon atom has 4 outermost electrons which shares share s with 4 valence electrons of four chlorine atoms(each chlorine atom has one valence electron).Thus, CCl4 has four single covalent bonds.

4.

A red and tall dominant character hybrid plant is crossed with recessive white dwarf plant (RrTt × rr tt). What W hat will be the ratio of respective four combinations : red tall, red dwarf, white tall and white dwarf plants in the next generation gener ation ? (A) 9 : 3 : 3 : 1 (B) 15 : 1 : 0 : 0 (C) 9 : 3 : 4 : 0

(D*) 4 : 4 : 4 : 4