Basics of Everyday Science MCQ — 193 Practice Questions with Answers

Explanation

Statement 1 is correct because hydrogen fuel cells combine hydrogen and oxygen to produce electricity, heat and water. Statement 2 is correct because the hydrogen-powered passenger vessel used low-temperature PEM technology and had only water as the byproduct. Statement 3 is incorrect because the byproduct at the point of use is water, not carbon dioxide.

Explanation

Candela (cd) is the SI base unit of luminous intensity. It measures the power emitted by a light source in a particular direction, weighted by the luminosity function. It is one of the seven SI base units along with metre, kilogram, second, ampere, kelvin, and mole.

Explanation

Statement 1 is correct: gamma rays are at the high-energy end of the electromagnetic spectrum. Statement 2 is incorrect: radio waves have low-energy photons, while X-rays are far more energetic. Statement 3 is correct: electromagnetic radiation can be described as photons travelling in a wave-like pattern at light speed. Statement 4 is incorrect because visible light is roughly 400 to 700 nanometres, not 40 to 70 nanometres.

Explanation

Statement 1 is incorrect because Hahn and Strassmann bombarded uranium with neutrons and found barium in the products, not the reverse. Statement 2 is correct because Meitner and Frisch gave the theoretical explanation. Statement 3 is correct because control rods made of boron, cadmium or hafnium absorb neutrons to regulate the fission chain reaction. Statement 4 is correct because in SCRAM all rods are fully inserted to shut down the reactor.

Explanation

Statement 1 is correct: O negative blood lacks A, B and Rh(D) antigens and is used as a universal donor type in emergencies. Statement 2 is incorrect because AB positive is the universal recipient, not universal donor. Statement 3 is correct: a sphygmomanometer measures arterial blood pressure.