General Science Mixed Quiz: Set 83

Inertia depends only on mass, and a cricket ball is the heaviest of the four. Inertia is the tendency of a body to stay at rest or keep moving uniformly in a straight line unless a force acts on it; this is Newton's first law.

A beam seen from the side is visible only because tiny particles send some of its light sideways. Light travelling in a straight line cannot enter our eyes unless something redirects it towards us.

Energy equals power multiplied by time: 0.1 kW × 30 hours = 3 kWh, which is 3 units. The bulb's power is 100 W, which is 0.1 kW.

Rotational kinetic energy is ½Iω², and the ring has the larger moment of inertia. For a thin ring about the axis through its centre and perpendicular to its plane, all the mass sits at distance R, so I = MR².

Only the gravitational field of a spherical body and the electrostatic field of a point charge fall off as 1/r².

One parsec equals about 2,06,265 astronomical units, which rounds to 2 × 10⁵ A.U.

A kelvin and a degree Celsius are the same size, but the Kelvin scale starts at absolute zero, which is −273.15 °C. The kelvin is the SI unit of temperature.

An ion-exchange resin or zeolite swaps the calcium and magnesium ions that cause permanent hardness for sodium or hydrogen ions.

A simple periscope has two plane mirrors facing each other in parallel, each tilted at 45° to the tube. Light from the object enters the top opening and strikes the upper mirror, which is set at 45° and turns the light through 90° down the tube.

Opium is the dried latex of the opium poppy, whose botanical name is Papaver somniferum; the second word means sleep bringing.

Dissolved salts make sea water less compressible, so sound travels faster in it, about 1,530 m/s at 25 °C, than in pure or drinking water.

Marie Curie discovered radium; the first two pairs have their discoveries swapped. Marie Curie and Pierre Curie discovered the radioactive elements polonium and radium in 1898, and Marie Curie went on to win Nobel Prizes in both physics (1903) and chemistry (1911).

In a uniform field the two poles of the magnet feel equal and opposite forces, which cancel each other.

Marsilea is a water fern, a pteridophyte, and pteridophytes are the first land plants with true vascular tissues, xylem and phloem.

Any particle smaller than an atom is a subatomic particle, and the muon qualifies just as the electron, proton and neutron do.

When electricity is passed through a sealed tube holding neon at low pressure, the gas atoms are excited and give out a bright orange-red glow, which is why advertising signs are still called neon signs.

This is a double displacement (precipitation) reaction, in which no element gains oxygen or loses electrons. When the two solutions are mixed, the ions swap partners: BaCl2 + Na2SO4 → BaSO4 + 2NaCl.

When the two mix, they release a rush of carbon dioxide that pushes water out onto the fire. In a soda-acid extinguisher a small bottle of dilute sulphuric acid sits inside a cylinder filled with a solution of sodium hydrogencarbonate (baking soda, NaHCO3).

The product forms a coating that shuts the acid out. Calcium reacts with dilute sulphuric acid to give calcium sulphate and hydrogen gas: Ca + H2SO4 gives CaSO4 + H2.

Vitamin C has no carboxyl group; its acidity comes from an enol group in its ring. Ascorbic acid, C6H8O6, is a five-membered lactone ring carrying hydroxyl groups.