Option “4” is correct. The SI unit of frequency is the hertz (Hz), named after the German physicist Heinrich Hertz; one hertz means that an event repeats once per second.
312. Which one of the following is an insulator?
1. Copper
2. Wood
3. Mercury
4. Aluminium
Option “2” is correct. Wood is a good insulator.
313. Bubbles of air rise up through liquids due to:
1. Surface tension and adherence
2. Viscosity and buoyancy
3. Air current over the liquid and buoyancy
4. Up thrust and surface tension
Option “2” is correct. Bubbles of air rise up through liquids due to viscosity and buoyancy.
314. Which one of the following is an insulator?
1. Copper
2. Wood
3. Mercury
4. Aluminum
Option “2” is correct. Wood is an insulator.
315. Formula for distance is –
1. Speed x time
2. Time / speed
3. Speed x acceleration
4. Velocity / speed
Option “1” is correct. Distance=Speed × Time
316. What is the fundamental unit of amount of a substance?7
1. Mole
2. Candela
3. Kelvin
4. Meter
Option “1” is correct. The mole is the unit of measurement for amount of substance in the International System of Units (SI). The unit is defined as the amount or sample of a chemical substance that contains as many constitutive particles.
317. Arithmometer was invented by –
1. Evangelista Torricelli
2. Charles Xavier Thomas
3. Edward Teller
4. Charles Babbage
Option “2” is correct. The Arithmometer was the first digital mechanical calculator strong enough and reliable enough to be used daily in an office environment. It was invented by Charles Xavier Thomas.
Option “2” is correct. National Science Day is celebrated in India on 28 February each year to mark the discovery of Raman Effect by Indian physicist C.V.Raman on 28 February 1928.
Option “3” is correct. Swedish scientist Alfred Nobel invented dynamite. The famous Nobel Foundation was established on the basis of his last will in 1900.
320. Which one of the following is used as antifreeze for the automobile engines?
