# Chemistry in Our Lives

UNIFIED COUNCIL
A n I S O 9 0 0 1 : 2000 C e r t i f i e d O r g a n i s a t i o n

NATIONAL LEVEL SCIENCE TALENT SEARCH EXAMINATION - 2011
SOLUTIONS FOR CLASS : 9
Mathematics
1. (A)
∠AME = 80° = ∠BMN ∠MND = 180 0 − 80 0 = 100 0

6.

(D)

x x 3 − 3x 2 + 2x / x /

(

)

∴ remainder = 0 Quotient : x3  3x2 + 2x

In ∆MNQ, ∠MNQ + ∠NMP + ∠MQN = 1800 (or)

1 1 × 1000 + × 80 0 + ∠MQN = 180 2 2

7.

(D)

xy 1 1 1 =a⇒ = + x+y a x y

⇒ ∠MQN = 1800 − 900 = 900
2. (D)

1 1 1 1 = 1 +1 = + , b x z c y z
1 1 2 1 1 2 1 + = + +  = + a b x y z x c

y=a+

b x 1 b 5

1 = a − b and 5 = a − ⇒ a = 6 and b = 5
∴ a + b = 6 + 5 = 11

2 1 1 1 bc + ac − ab = + − = abc x a b c 2abc bc + ac − ab
8 Z 5 Y

⇒x=
8. (C)

3.

(B)

V = πr 2 h

X 2

x y = 2 + 8 + 5 = 15

= πa b
2

∴ X-U-Z-Y

9. 10.

(C) (C)

4.

(D)

Sum of n of observations = mn of O & m are added the sum = mn + 0 + m = m (n+1) No. of observations = n+2

∆ ABC ≈ ∆ DBE, ∆ DEF, ∆ ADF, ∆ ECF AB//CD//EF
⇒ ar • ∆AGB = 1 | |gm AEFB 2

[Q ∆AGBand| |gm AEFB
A E D G C B F

5.

(B)

m(n + 1) n+2 In a leap year, there are 366 days, i.e., 52 weeks and 2 days. ∴ New mean =
To have 53 sundays in the year, the extra day must be saturday, sunday or sunday, monday. so, required probability =

are on the same base and between same parallel lines AB and EF]

1 S ∴ar ∆AGB = | gm ABCD = . | 4 4
11. (B)

2 7

∠AQP = =

1 ∠AOP 2

1 × 750 = 37.50 2
(9_Class)_NAT_Solutions

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12.

(A)

a3 27 = 3 a1 1
a = a1
3

x2 = 10 4 : 3 is not the ratio of dimensions of the rectangle. 22. (C) OA = OB = AD= (1) (2)

27 3 = 1 1

13 = 6.5 cm 2

13.

(C)

Chicken = x goat = y x+y = 30 2x+4y = 84 chicken = 18,

5 12 = 6 cm, BC= = 2.5 cm 2 2

C B A D O
In ∆ADO, DO = 2.5 cm In ∆BCO CO = 6 cm Distance between the two chords CD = CO - OD = 6 - 2.5 = 3.5 cm. 23. (B) Q=5- 2 6

Sol. (1) & (2) we get goat...