I'll be happy to help you with the solutions to these questions. Here are the answers:

Question 1: This question does not have any options.

Question 2: (A) Both A and R are true, and R is the correct explanation of A.

Question 3: D

Question 4: B. Smaller large intestine in herbivores helps in digesting cellulose.

Question 5: C. Posture and balance is disturbed.

Question 6: D In snails individuals can begin life as male and depending on environmental conditions they can become female as they grow.

Question 7: B. A ray parallel to the principal axis will give the minimum angle of incidence as zero.

Question 8: Colour of Ray A = Blue Colour of Ray B = Violet

Question 9: C The energy available to producers is maximum because plants (producers) absorb most light energy and transfer only a small part to consumers, using that remainder, for its own respiration, growth, reproduction, movement etc.

Question 10: B. Smaller large intestine in herbivores helps in digesting cellulose.

Question 11: D. Regulation of blood pressure is disturbed.

Question 12: D In snails sex is not genetically determined but rather based on environmental factors.

Question 13: A A ray parallel to the principal axis will give the minimum angle of incidence as zero.

Question 14: Red Violet - C

Question 15: D The energy available to producers cannot be transferred due to the high losses (about 90%) in each trophic level.

Question 16: B Enrichment of oxygen in atmosphere is incorrect role for decomposers, instead, enrich decomposition process when a decomposer disassembles dead organisms and replenish soil nutrients back into the system.

Question 17: Assertion (A): When HCL was added to the test tube containing a substance‘X’, it forms hydrogen gas (H2) with a characteristic ‘pop sound’ is not obtained due to the substance ‘X’.

Reason (R): In this reaction metal ‘X’ is displaced by Hydrogen is incorrect. The characteristic 'pop sound' when a burning match stick was brought near is due to the reaction of HCl and the hydrogen gas it forms.

1. Question 18: Assertion (A): The number of chromosomes in a cell and in a germ cell are not the same in any species.

Reason (R): This statement is true and correct explanation.

1. Question 19: Assertion (A): A convex mirror will form an image behind and this image formed virtual.

However, in the case of Convex Mirror, only when ray enters through the center then it forms a virtual Image beyond the curvature or if it is refracted at a very low angle then we can see it forming on a screen. In all other cases rays get reflected with more intensity (which results into virtual images). The reason behind this statement false as its not possible for convex mirror to produce real-image.

1. Question 20: Assertion (A): If the plants that are removed from an ecosystem will not affect the food chain however if lions are removed then the food chain is disturbed

Reason (R): When the plant is removed, it disrupts the entire chain of nutrient flow and thus affects the ecosystem whereas removal of the lions only disrupt that specific trophical levels