All Free Everyday Science MCQs with Answers

1791. X-rays were discovered by __________?

• A. Wilhelm Conrad Roentgen
• B. Thomson
• C. Ernest Rutherford
• D. Bacquerel

Explanation: Wilhelm Conrad Röntgen discovered X-rays in 1895 while experimenting with cathode-ray tubes. Thomson, Rutherford, and Becquerel made other major discoveries in atomic and radiation science.

1792. Central Color of Rainbow is__________?

• A. Blue
• B. Green
• C. Red
• D. Indigo

Explanation: A rainbow's colors run from red on the outer edge to violet on the inner edge, with green near the middle. This arrangement results from dispersion of sunlight in raindrops.

1793. Candela is the basic unit of_________________?

• A. luminous intensity
• B. heat producing value
• C. Thermodynamic temperature
• D. radioactive decay

Explanation: Candela is the SI base unit of luminous intensity, the amount of light emitted in a particular direction. Temperature, heat value, and radioactive decay have different units.

1794. Steradian is the unit of_______________?

• A. Solid angle
• B. Liquid angle
• C. Gas angle
• D. Plain angle

Explanation: A steradian measures a solid angle in three-dimensional space, just as a radian measures a plane angle in two dimensions. Liquid and gas are not types of angle units.

1795. Siemens is the unit of__________________?

• A. Electrical Conductance
• B. Magnetic Conductance
• C. Electrical Capacitance
• D. Magnetic Capacitance

Explanation: The siemens is the SI unit of electrical conductance, which is the reciprocal of resistance: S = 1/Ω. Capacitance is measured in farads, not siemens.

1796. The temperature at which water boils depends mainly on ____________?

• A. Air temperature
• B. Relative humidity
• C. Air pressure
• D. Air density
• E. The specific heat of air

Explanation: Boiling occurs when a liquid's vapour pressure equals the surrounding pressure, so water boils at a lower temperature on high mountains and a higher temperature in a pressure cooker. Air temperature and humidity do not primarily set the boiling point.

1797. The total energy of revolving electron in an atom_____________

• A. Will always be positive
• B. Can never be positive
• C. Can have any value above zero
• D. Cannot be negative

Explanation: An electron bound to an atom has negative total energy when zero energy is defined as the electron completely free from the atom. A positive total energy would describe an unbound electron, so “can never be positive” is the intended choice.

1798. Select the arrangement of electromagnetic radiation which starts with the lowest energy and increases to greatest energy?

• A. radio, visible, infrared, ultraviolet, x-ray, gamma ray
• B. radio, infrared, visible, x-ray, gamma ray, ultraviolet
• C. visible, radio, infrared, ultraviolet, x-ray, gamma ray
• D. radio, infrared, visible, ultraviolet, x-ray, gamma ray

Explanation: Energy increases with frequency and decreases with wavelength: radio, infrared, visible, ultraviolet, X-rays, then gamma rays. Therefore option d gives the correct low-to-high energy order.

1799. Which of the following has the largest wavelength?

• A. visible light
• B. x-rays
• C. infrared light
• D. ultraviolet radiation

Explanation: Infrared has a longer wavelength than visible light, ultraviolet radiation, and X-rays. In the electromagnetic spectrum, wavelength decreases as frequency and energy increase.

1800. Which of the following has the highest energy?

• A. gamma rays
• B. X-rays
• C. Ultra-violet radiation
• D. radio waves

Explanation: Gamma rays have the highest frequency and therefore the highest energy among the listed electromagnetic radiations. Radio waves have the lowest frequency and energy in this set.