General Science Mixed Quiz: Set 9

A lactometer floats in milk and shows its relative density. Pure milk is denser than water, so adding water lowers the density and the instrument sinks deeper, which reveals the adulteration.

A qubit, short for quantum bit, is the basic unit of information in a quantum computer.

Milk contains very little vitamin C, and what little there is gets destroyed further when milk is boiled. Milk is otherwise called a nearly complete food: it gives calcium and phosphorus for bones and teeth, good-quality protein, mainly casein, the sugar lactose, fat, and vitamins A, B2 and B12.

Isaac Newton built the first practical reflecting telescope in 1668. In it, light from the star falls on a large concave mirror at the bottom of the tube, and a small flat mirror set at 45 degrees near the top turns the light sideways to the eyepiece.

The stapedius, only about 1 millimetre long, is the smallest skeletal muscle in the human body. It lies in the middle ear and is attached to the stapes, which is itself the smallest bone of the body.

Air always moves from a region of higher pressure to one of lower pressure, so it flows out of the lungs only when the pressure inside them rises above that of the outside air.

The torr is a unit of pressure named after Evangelista Torricelli, the Italian scientist who invented the mercury barometer in 1643.

A person with AB positive blood can receive red cells from every ABO and Rh group, so AB+ is called the universal recipient.

The liver needs vitamin K to make prothrombin and other clotting factors, so without it blood takes much longer to clot.

The pancreas is both an exocrine gland, pouring digestive enzymes into the intestine, and an endocrine gland. Its endocrine part is made of small clusters of cells called the islets of Langerhans.

Newton's second law gives force = mass × acceleration. Mass has the dimension [M], and acceleration is velocity divided by time, that is [L T⁻¹] ÷ [T] = [L T⁻²].

In DNA, adenine always pairs with thymine through two hydrogen bonds, and guanine pairs with cytosine through three. This is called complementary base pairing, and it is why one strand of DNA can be used to copy the other.

The liver needs vitamin K to make several clotting factors, including prothrombin, which help blood form a clot and seal a wound.

At great heights the air is thin, so the atmospheric pressure acting on the body is much lower than at sea level.

Pressure is force acting per unit area, so its SI unit is the newton per square metre, which is given the special name pascal (Pa) after the French scientist Blaise Pascal, who stated the law of transmission of pressure in liquids used in hydraulic brakes and lifts.

The cooking temperature is set by the pressure inside the cooker, and that pressure is fixed by the weight sitting on the vent and the area of the hole under it.

Vitamin K is needed to make the clotting proteins, so without it even a small cut keeps bleeding. The liver uses vitamin K to make prothrombin and other clotting factors that turn blood into a clot at a wound.

Luminous intensity is the amount of visible light a source sends out in a given direction per unit solid angle, and its SI base unit is the candela (cd), roughly the light of one ordinary candle.

Vitamins A, D, E and K dissolve in fat, while the B group and vitamin C dissolve in water.

One ampere is the current that flows when one coulomb of charge passes a point in a circuit in one second.