General Science Questions and Answers

Answer: A

Only (1) is correct: Mars is the planet Mangalyaan went to.

Pinatubo is a volcano in the Philippines, not Japan, the crust is the outermost layer, not the inner, and Ganymede is a moon of Jupiter, not Saturn. So (1) alone, option A.

Mangalyaan, the Mars Orbiter Mission, was launched by ISRO in 2013. Pinatubo is a volcano of the Philippines, not Japan, the crust is the outermost layer of the Earth, not the inner, and Ganymede is the largest moon of Jupiter, not Saturn's moon. So only the first pair is right.

Answer: B

Earthquakes are measured by a seismograph.

A seismograph (seismometer) detects and records the ground waves an earthquake produces; the record is a seismogram, from which the magnitude (for example on the Richter or moment magnitude scale) and the epicentre are worked out.

A mammograph is a medical X-ray machine for breast imaging. A speedometer shows a vehicle's speed, and an anemometer measures wind speed.

Answer: A

The keyed answer is 28 days.

The moon takes about 27.3 days to complete one orbit of the earth measured against the stars (the sidereal month), and about 29.5 days from one new moon to the next (the synodic month, the cycle of phases). Twenty-eight days is the usual round figure between the two, and it is the only option anywhere near either.

The other choices, 45, 50 and 65 days, are all far longer than any measure of the moon's orbit, so they can be ruled out at once.

Answer: A

The Big Bang theory explains the origin of the universe.

It holds that the universe began about 13.8 billion years ago from an extremely hot and dense state and has been expanding and cooling ever since. The evidence includes the expansion of the universe (galaxies moving apart) and the cosmic microwave background radiation left over from the early universe.

The origin of the sun and the solar system, about 4.6 billion years ago, is explained by the nebular theory, a much later event. The Big Bang is not a law of chemistry, and it has nothing to do with history.

Answer: C

The nearest planet to the sun is Mercury.

Mercury orbits the sun at an average distance of about 58 million km, closer than any other planet, and completes an orbit in 88 days. It is also the smallest planet of the solar system.

The order outward from the sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Venus is second, Mars fourth and Jupiter fifth, so none of them is the nearest.

Answer: B

The hottest planet is Venus.

Venus has a surface temperature of about 465°C, hot enough to melt lead. Its dense atmosphere, mostly carbon dioxide, traps heat in a runaway greenhouse effect, so the temperature stays high across the planet, day and night.

The trap is Mercury, which is closer to the Sun but has almost no atmosphere: its day side reaches about 430°C, but the heat escapes and its night side falls far below freezing. Mars and Jupiter are much colder.

Answer: A

A solar eclipse occurs when the Moon is between the Sun and the Earth.

When the Moon passes directly between the Sun and the Earth, at new moon, its shadow falls on part of the Earth and blocks the Sun's light there.

When the Earth is between the Sun and the Moon, the Earth's shadow falls on the Moon, which is a lunar eclipse. The Sun can never be between the Earth and the Moon, since the Moon orbits the Earth.

Answer: D

Clothes dry earliest at 20% RH 60°C temperature.

Drying is evaporation, which is fastest when the air is warm and dry. High temperature gives water molecules more energy to escape, and low relative humidity means the air can take up much more water vapour.

At 100% relative humidity the air is already saturated, so clothes hardly dry at either temperature. At 80% humidity and 20°C drying is slow, so the hot, dry condition wins.

Answer: C

The key's answer is the bottom.

The textbook reason is pressure: the weight of the ice above presses on the base of a glacier, and higher pressure lowers the melting point of ice. Heat from the ground below and friction from the moving ice add to it, so melting starts at the bed, and the meltwater lubricates the glacier's slide.

The top surface, sides and middle are under less pressure and so have a higher melting point, which is why the key rules them out.

Answer: D

The pulmonary artery carries impure, deoxygenated blood - from the right ventricle to the lungs.

It is the one artery that does so; the pulmonary vein is likewise the one vein carrying oxygenated blood, from the lungs back to the left atrium. The rule that arteries carry pure blood fails for exactly this pair.