A body is projected vertically upward with velocity 20 m/s. Maximum height reached is (g=10 m/s^2):
A. 10 m
B. 20 m
C. 40 m
D. 5 m
Correct Answer: B H = u^2/2g = 400/20 = 20 m.
Q2. Physics
The Doppler effect in sound is observed when there is relative motion between source and:
A. Observer only
B. Medium only
C. Observer or source
D. Neither
Correct Answer: C Doppler effect occurs when source or observer is in motion relative to each other.
Q3. Chemistry
What is the molecular formula of the compound with the empirical formula CH2O and a molecular weight of 180 g/mol?
A. C6H12O6
B. C3H6O3
C. C2H4O2
D. C4H8O4
Correct Answer: A The empirical formula of the compound is CH2O, and its molecular weight is 180 g/mol. The empirical formula weight is 30 g/mol (12 for C, 2 for H, and 16 for O). To find the molecular formula, we divide the molecular weight by the empirical formula weight: 180/30 = 6. Therefore, the molecular formula is (CH2O)6, which is C6H12O6.
Q4. Chemistry
Which of the following is a strong acid?
A. CHCOOH
B. HCl
C. HCO
D. HS
Correct Answer: B HCl completely dissociates in water -> strong acid.
Q5. Mathematics
The probability of getting a head when a fair coin is tossed is:
A. 0
B. 1/4
C. 1/2
D. 1
Correct Answer: C P(Head) = 1/2 (favorable outcomes / total outcomes).
Q6. Physics
A wire of resistance R is stretched to double its length. New resistance will be:
A. R/2
B. R
C. 4R
D. 2R
Correct Answer: C When length is doubled (L' = 2L), cross-sectional area halves (A' = A/2). R' = L'/A' = (2L)/(A/2) = 4L/A = 4R.
Q7. Mathematics
If the equation of a circle is x^2 + y^2 + 4x - 6y + 9 = 0, what is the radius of the circle?
A. 2
B. 4
C. sqrt(5)
D. sqrt(5)
Correct Answer: D To find the radius of the circle, we need to rewrite the equation of the circle in the standard form (x - h)^2 + (y - k)^2 = r^2, where (h, k) is the center of the circle and r is the radius. Completing the square for x and y, we get (x + 2)^2 - 4 + (y - 3)^2 - 9 + 9 = 0, which simplifies to (x + 2)^2 + (y - 3)^2 = 4. Comparing this with the standard form, we see that the radius is sqrt(4) = 2.
Q8. Physics
Which of the following has the highest penetrating power?
A. -rays
B. -rays
C. -rays
D. UV rays
Correct Answer: C Gamma rays have the highest penetrating power due to their high energy and no charge.
Q9. Mathematics
The nth term of AP: 2, 5, 8, 11... is:
A. 3n - 1
B. 3n - 1
C. 2n + 1
D. n + 2
Correct Answer: B a = 2, d = 3, T = 2 + (n-1)3 = 3n - 1.
Q10. Physics
The speed of sound is maximum in:
A. Air
B. Water
C. Steel
D. Vacuum
Correct Answer: C Sound travels fastest in solids (steel ~5000 m/s) due to close molecular arrangement.
Q11. Mathematics
The value of log 32 is:
A. 4
B. 5
C. 6
D. 3
Correct Answer: B log 32 = log 2 = 5.
Q12. Physics
The de Broglie wavelength of an electron moving with velocity v is . If velocity is doubled, wavelength becomes:
A. 2
B. /2
C. 4
D. /4
Correct Answer: B = h/p = h/(mv). If v doubles, ' = h/(m.2v) = /2.
Q13. Physics
If the distance between two charges is halved, the force between them becomes:
A. Half
B. Double
C. Four times
D. Same
Correct Answer: C F 1/r^2. If r -> r/2, F -> 4F.
Q14. Physics
A block of mass 2 kg is moving with a velocity of 3 m/s on a frictionless surface. What is the kinetic energy of the block?
A. 9 J
B. 6 J
C. 12 J
D. 4 J
Correct Answer: A Kinetic energy = (1/2)mv^2 = (1/2)*2*3^2 = 9 J.
Q15. Chemistry
How many moles of O are required for complete combustion of 1 mole of CH?
A. 4
B. 5
C. 6.5
D. 8
Correct Answer: C CH + 6.5O -> 4CO + 5HO. So 6.5 moles of O are needed.