General Science Mixed Quiz: Set 82

Momentum is a vector, and on bouncing the ball's direction of motion reverses at once, from downward to upward. Just before impact the ball moves down with velocity v, so its momentum is mv downward.

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.

Gravity is a conservative force, so the work it does never depends on the path. The work done by gravity on a body of mass m is mgh, where h is the vertical height between the start and the end.

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.

Doubling one mass doubles the force, while doubling the distance cuts it to one-fourth, so the net result is 2 × 1/4 = 1/2.

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

One kelvin and one degree Celsius are the same size, so a rise of 30 K is also a rise of 30°C. The Kelvin and Celsius scales differ only in their starting point: T(K) = t(°C) + 273 (more exactly 273.15).

Together the two resins take out every dissolved ion, which leaves demineralised water. In the cation exchange resin (written RH), metal ions such as Ca2+, Mg2+ and Na+ are swapped for H+ ions.

A plane mirror always forms a virtual image, one that cannot be caught on a screen, so calling it real is the false statement.

Glass is made by melting silica sand with fluxes and stabilisers, and this option lists the standard batch. Silica, from pure sand, forms the glassy network.

Pitch is how high or low a sound seems to the ear, and it depends on the frequency of vibration: the higher the frequency, the higher the pitch.

Gamma rays sit at the far end of the electromagnetic spectrum, with the shortest wavelength and therefore the highest frequency and energy.

Each piece has a resistance of 10 ohm, and five equal 10-ohm resistors in parallel give 10 ÷ 5 = 2 ohm.

The zygote divides as it travels down the fallopian tube and the resulting ball of cells gets implanted in the thick lining of the uterus.

The atomic number (Z) is defined as the number of protons in the nucleus of an atom. Every atom of an element has the same number of protons, so the atomic number identifies the element: hydrogen has 1, carbon 6 and oxygen 8.

The hepatitis B vaccine was the first vaccine made by recombinant DNA technology.

Slaked lime is calcium hydroxide applied as a watery solution, and it takes up carbon dioxide gas from the air to form solid calcium carbonate and water.

Hypobromous acid has one hydrogen, one oxygen and one bromine atom, with bromine in the +1 oxidation state. The oxyacids of a halogen are named by how much oxygen they hold.

Magnesium is above hydrogen in the reactivity series, so it displaces hydrogen from the acid: Mg + 2HCl → MgCl2 + H2.

Buckminsterfullerene is C60, a cage-shaped molecule of sixty carbon atoms. The sixty atoms are arranged in 12 pentagons and 20 hexagons, the same pattern as the panels of a football, which is why the molecule is also called a buckyball.