General Science Mixed Quiz: Set 208

With no net force acting on it, the object keeps moving at the same speed in the same straight line.

An angiosperm shows double fertilisation: of the two male gametes brought by the pollen tube, one fuses with the egg to give a diploid zygote, and the other fuses with the two polar nuclei of the central cell.

G has the same value everywhere in the universe, for any two masses. The relation is Newton's law of universal gravitation: every two bodies attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

The thyroid is a butterfly-shaped gland in the neck, in front of the windpipe, and is the largest of the ductless or endocrine glands; it secretes thyroxine, for which iodine is essential, and the hormone controls the rate of metabolism, growth and development.

This is the Clausius statement of the second law. Rudolf Clausius stated that heat cannot by itself pass from a colder body to a hotter one; work must be done to make it do so.

The potato is Solanum tuberosum, and the epithet tuberosum points to the tuber, a swollen underground stem rather than a root, which is the part eaten; the plant belongs to the nightshade family and reached India through the Portuguese.

An angle of incidence of 0° means the ray falls along the normal, and a ray along the normal passes into the next medium without bending.

Seismology is the study of earthquakes and of the passage of seismic waves through the earth, and it is from seismic wave records that the layered structure of the interior of the earth has been worked out; the instrument used is the seismograph.

Bats send out ultrasonic squeaks and listen for the echoes to locate obstacles and prey. This method is called echolocation.

In a single fixed pulley the rope that is pulled down moves exactly as far as the load rises, so the distance moved by the effort equals the distance moved by the load and the velocity ratio is one; the pulley gives no gain in force and is used only…

In an insulator the electrons are tightly bound to their atoms, so there are almost no free electrons to carry a current.

Water contracts as it is cooled to four degrees, is densest at that temperature, and then expands again as it cools further to zero, which is called the anomalous expansion of water.

Tritium is the only radioactive isotope of hydrogen; its nucleus is unstable and decays by giving out beta particles. Hydrogen has three natural isotopes, all with one proton but different numbers of neutrons.

One faraday is the charge carried by one mole of electrons, obtained by multiplying the charge on a single electron by the Avogadro number, and it comes to about 96,500 coulombs; passing one faraday through an electrolyte liberates one gram equivalent of the substance at an electrode.

Phosphorus has five electrons in its outer shell and shows two common valencies, 3 and 5. Phosphorus, atomic number 15, has the electronic configuration 2, 8, 5.

Boyle's law, established in 1662, says that for a fixed mass of gas at constant temperature the product of pressure and volume stays constant, so doubling the pressure halves the volume.

Silver sits near the bottom of the reactivity series and does not combine with oxygen even when heated in air.

The so-called lead of a pencil is a mix of graphite and clay; it contains no lead metal. Graphite is a crystalline form, or allotrope, of carbon.

Washing soda is the crystalline form of sodium carbonate, Na2CO3·10H2O, sodium carbonate decahydrate. Sodium carbonate is made from common salt by the Solvay (ammonia-soda) process.

A prokaryotic cell has no true nucleus, so its genetic material is not wrapped in a nuclear membrane. Bacteria and cyanobacteria are prokaryotes.