Free NEET MCQ Test Questions and Answers

Question 1

What is true about the following statements?

Accepted Answer

All Chondrichthyes are marine animals with a streamlined body with some exceptions

Answer

Chondrichthyes, or cartilaginous fishes (e.g., sharks, rays), are predominantly marine animals characterized by a streamlined body and a cartilaginous skeleton. While most species are found in marine environments, there are indeed some exceptions, such as certain rays and sharks that can inhabit brackish or freshwater. This statement accurately captures their general characteristics with the important nuance of exceptions.

Question 2

A table tennis ball with a conducting tip on it hangs between two metal plates and is supported by a thin thread. One plate is connected to the earth, while the other is to a high-voltage generator, with the ball in between.

Accepted Answer

Swings backward & forward hitting each plate in turn

Answer

When the conducting ball touches the high-voltage plate, it acquires the same charge and is then repelled by that plate while being attracted to the earthed plate. Upon contact with the earthed plate, the ball discharges or acquires an opposite charge, causing it to be repelled by the earthed plate and attracted back to the high-voltage plate. This continuous cycle of attraction and repulsion results in the ball swinging back and forth between the two plates.

Question 3

The corners of a cubic unit cell in a solid "AB" with a NaCl structure are occupied by "A" atoms. The solid's resulting stoichiometry is as follows if all the atoms with faces to one of the axes are eliminated:

Accepted Answer

A3B4

Answer

In a solid with a NaCl structure, one type of atom (A) forms an FCC lattice (corners and face centers), and the other (B) occupies octahedral voids (edge centers and body center), resulting in A4B4 initially. If atoms on faces perpendicular to one axis are eliminated, this typically refers to the two face-centered atoms on those opposite faces. These are A atoms, and each contributes 1/2 to the unit cell, so 1 A atom is effectively removed. B atoms, being at edge centers and the body center, are not affected. Thus, the stoichiometry becomes A3B4.

Question 4

Which of the following metal pollutants found in vehicle exhaust is the most hazardous?

Accepted Answer

Lead

Answer

Lead is widely recognized as the most hazardous metal pollutant found in vehicle exhaust. It is a neurotoxin that can cause severe developmental and neurological problems, especially in children, even at low exposure levels. Historically, leaded gasoline was a major source of environmental lead contamination, leading to widespread health concerns before its phase-out.

Question 5

Which of the following about the myelin sheath is incorrect?

Accepted Answer

Myelin sheath is seen only as an outermost layer of a whole Schwann cell.

Answer

The statement that the myelin sheath is seen only as an outermost layer of a whole Schwann cell is incorrect. While Schwann cells do form the myelin sheath in the peripheral nervous system, the myelin itself is a multi-layered lipid-rich membrane that wraps around the axon, not just a single outermost layer. It is secreted by Schwann cells (PNS) and oligodendrocytes (CNS) and acts as an insulating layer, with gaps called Nodes of Ranvier.

NEET - National Eligibility cum Entrance Test Practice Test

NEET - National Eligibility cum Entrance Test Practice Test

Free NEET MCQ Test Questions and Answers