Science in Class 10 : Practice MCQ Questions & Answers with Explanations

The iris regulates the size of the pupil, controlling the amount of light that enters the eye. It adjusts according to light conditions for optimal vision.

The speed of light in a vacuum is approximately $3 \times 10^8\ \text{m/s}$, a fundamental constant used in many physics equations.

The pituitary gland, located at the base of the brain, controls other glands including the thyroid, adrenal glands, and reproductive glands.

Nerve cells (neurons) are the longest cells in the human body. Some extend from the spinal cord to the extremities, enabling communication over long distances.

Bauxite is the primary ore from which aluminum is extracted through a refining process.

Photosynthesis is the process by which plants convert sunlight, water, and carbon dioxide into glucose and oxygen, providing energy for growth.

Kidneys are part of the excretory system, responsible for filtering waste from the blood. The heart, blood, and lungs are components of the circulatory system.

Stomata are small pores on leaf surfaces that allow the intake of carbon dioxide, which is necessary for photosynthesis, while also facilitating gas exchange.

Acids turn blue litmus paper red. This color change is used to identify acidic substances on the pH scale.

Decomposers like fungi and bacteria break down dead organic matter into simpler substances, recycling nutrients back into the ecosystem.

Nitrogen oxides and sulfur dioxide from industrial emissions combine with water vapor in the atmosphere to form acid rain.

Smog is primarily composed of carbon monoxide, nitrogen oxides, and other pollutants that combine with particulate matter to create a haze, reducing visibility and harming health.

A solenoid creates a magnetic field when current passes through it, similar to the field produced by a bar magnet, with distinct north and south poles.

An ammeter measures the current (flow of electric charge) in a circuit. It is connected in series with the circuit.

The SI unit of electric current is the ampere (A). One ampere represents one coulomb of charge passing through a conductor per second.

When light passes through a prism, different wavelengths refract by different amounts, causing white light to spread into its constituent colors — this is dispersion.

The focal length is the distance from the lens to the point where light rays converge (focus). It determines the lens's ability to bend light.

When light enters a denser medium such as water from air, it slows down and bends towards the normal line due to refraction.

The law of reflection states that the angle at which light strikes a reflective surface (angle of incidence) equals the angle at which it is reflected (angle of reflection).

The father contributes either an X or Y chromosome. XX results in a female and XY results in a male, so the father's contribution determines the sex of the baby.