Units and Measuring Instruments

A 100 watt bulb consumes 100 watts per hour. To consume 1 kilowatt-hour (1000 watt-hours), it takes 1000/100 = 10 hours. Hence, the bulb consumes one unit of electricity in 10 hours.

Atomic clocks are the most accurate devices for measuring very small time intervals due to their use of the consistent frequency of atomic transitions.

746 watts is approximately equal to 1 horsepower (HP). This is a standard conversion used in physics and engineering to relate power units.

The Beaufort Scale is a standardized scale used to estimate and describe wind velocity based on observed sea conditions or land effects. It does not measure air pressure, wind direction, or humidity.

There are 10 millimeters in 1 centimeter, so in 10 centimeters there are 10 × 10 = 100 millimeters.

The instrument specifically used for viewing the Sun safely is called a solar telescope (also historically called a heliograph or photoheliograph). However, the term 'heliograph' in modern usage primarily refers to a signaling device that uses sunlight reflection to send messages, not an instrument for viewing the Sun. The options given include 'Stroboscope' (used to view fast-moving objects), 'Heliograph' (signaling device), 'Solograph' (not a recognized instrument), and 'None of these'. Since none of the options correctly name a solar telescope or a proper solar viewing instrument, the correct answer is 'D' (None of these). Viewing the Sun requires specialized solar telescopes or filters to protect the eyes, which are not represented by the other options.

A photometer is an instrument used to measure the intensity or brightness of light. Therefore, option B, 'Measuring light Intensity,' correctly describes the function of a photometer.

A chronometer is a precise instrument used to measure time, especially in navigation and scientific contexts. Therefore, the correct answer is 'Time'.

A fathom is a unit of length used especially for measuring the depth of water. It is equal to 6 feet or approximately 1.8 meters, making it the correct unit for measuring depth.

One yard is equal to exactly 3 feet. This is a standard unit conversion in measurement.

One gross is a unit of quantity equal to 12 dozen, which is 144 items. Therefore, option C (12 Dozen) is correct.

One kilogram is equal to approximately 35.274 ounces. This is based on the exact conversion where one ounce is defined as 28.349523125 grams, so 1 kilogram (1000 grams) divided by 28.349523125 grams per ounce equals about 35.274 ounces. Therefore, option D (35) is the closest and correct answer among the given options.

An ombrometer is the instrument used to measure the amount of rainfall, making it the correct answer for the instrument of a rain gauge.

A pluviometer is an instrument used to measure the amount of rainfall over a period of time, making option C the correct answer.

One ton (specifically a US ton or short ton) is equal to 907 kilograms approximately. This is the standard conversion used in everyday measurements.

One kilogram is approximately equal to 2.20 pounds. This is a standard conversion factor used in everyday measurements.

There are 16 ounces in one pound according to the standard US customary system of measurement, making option D correct.

One pound is equal to approximately 453 grams, which is the standard conversion used in most measurement systems.

One ounce is approximately equal to 28.35 grams, so the closest and correct option is 28 grams.

Eratosthenes was the first known person to accurately measure the Earth's circumference using the angles of shadows in different locations and basic geometry around 240 BCE.

Mass is the quantity of matter present in an object, distinguishing it from weight, which depends on gravitational force. Density relates mass to volume, so it is not the direct measure of quantity of matter.

The thickness of the ozone layer is measured in Dobson Units, which quantify the total amount of ozone in a column of the atmosphere.

A hypsometer is an instrument used to measure height or altitude above sea level by determining the boiling point of water, which changes with atmospheric pressure. The other options measure different parameters: a hygrometer measures humidity, a pyrometer measures high temperatures, and a solometer is not a standard instrument.

The standard unit for measuring home electricity consumption is the kilowatt-hour (kWh), which represents the energy used when one kilowatt of power is consumed for one hour. This unit is commonly used by electricity meters and billing systems.

A nephoscope is an instrument specifically designed to determine the direction of movement of clouds, making option A correct. Stethoscope is used for listening to internal body sounds, and metroscope is not a standard meteorological instrument.