Explanation

Centripetal force acts perpendicular to the direction of motion, so it does no work.

Work = Force × Displacement × cos(θ); since θ = 90°, cos(90°) = 0, so Work = 0.

Explanation

 When an object moves at constant speed, its acceleration is zero.  

According to Newton’s Second Law:  

F = ma → If a = 0, then F = 0

Explanation

Mass is a measure of an object's inertia — its resistance to changes in motion.

Unlike weight (which depends on gravity), mass is an intrinsic property and directly related to inertia.

Explanation

A cell counter is a device specifically designed to count the number of cells in a suspension.

This is crucial in cell culture experiments, as researchers need to know the cell concentration before seeding or performing other procedures. 

Explanation

In a reversible reaction, a catalyst reduces the time to reach equilibrium by increasing the rate of both forward and reverse reactions. 

Explanation

A crystal can only have one center of symmetry. 

A center of symmetry is a point within a crystal where, if a line is drawn through that point and extended an equal distance on the other side, it intersects an identical point on the crystal.

Since this is a single, specific point within the crystal, there can only be one center of symmetry per crystal. 

Explanation

In a line absorption spectrum, dark lines are due to transmittance.

In an absorption spectrum, dark lines appear against a continuous background.

These dark lines correspond to wavelengths of light that have been absorbed by the material through which the light passes.

The remaining wavelengths, which are not absorbed, are transmitted and create the bright background. 

Explanation

The number of loops in stationary waves depends on the wavelength of the waves. 

A longer wavelength means fewer loops fit within a given length, and vice versa, so the number of loops is directly related to the wavelength. 

Explanation

The reverse process of the photoelectric effect is the production of X-rays when electrons are decelerated.

In the photoelectric effect, light (photons) interacts with a material, causing electrons to be emitted.

Explanation

The SI unit of conductance is the Siemens (S).

It is the reciprocal of resistance, which is measured in ohms (Ω).

Therefore, 1 Siemens is equal to 1/ohm.

The term "mho" is also sometimes used as a unit of conductance, but Siemens is the standard SI unit.