16. Assertion (A): The earthworms reduce the fertility of the soil. Reason (R): They make the soil soft and porous.
(A) A is true, but R is false.
(B) A is false, but R is true.
(C) Both A and R is true.
(D) Both A and R is false.
Answer:
(B) A is false, but R is true.
Explanation:
Earthworms actually increase the fertility of the soil, making the assertion false. They achieve this by making the soil soft and porous, which improves aeration and water retention, so the reason is true.
17. A is the mother of B, B is the sister of C, C is the father of D. So, how A is related to D?
(A) Grandmother
(B) Mother
(C) Aunt
(D) Insufficient data
Answer:
(A) Grandmother
Explanation:
Since B is C’s sister, A (who is B’s mother) is also C’s mother. Because C is the father of D, A is the mother of D’s father, making A the grandmother of D.
18. What will be the missing letters in the series BKK, DMM, FOO, __, JSS?
(A) HTT
(B) HQQ
(C) HPP
(D) None of the above
Answer:
(B) HQQ
Explanation:
The first letters follow a +2 sequence: B (+2) D (+2) F (+2) H (+2) J. The second and third letters are identical and follow a +2 sequence: K (+2) M (+2) O (+2) Q (+2) S. Therefore, the missing term is HQQ.
19. Mach number is defined as
(A) The ratio of a mass number to weight
(B) The ratio of characteristic velocity to velocity of sound
(C) The ratio of force to velocity
(D) The ratio of friction to acceleration
Answer:
(B) The ratio of characteristic velocity to velocity of sound
Explanation:
In fluid dynamics, the Mach number is a dimensionless quantity representing the ratio of flow velocity past a boundary to the local speed of sound.
20. 1 liter of sewage, when enabled to settle for 60 minutes, gives a sludge volume of 36 cm3. If the dry weight of this sludge is 6 grams, find its sludge volume index?
(A) 12
(B) 10
(C) 6
(D) 14
Answer:
(C) 6
Explanation:
Sludge Volume Index (SVI) is calculated as the volume of settled sludge (in mL/L) divided by the concentration of suspended solids (in g/L). Thus, 36 mL / 6 g = 6 mL/g.
