Free Technology and Energy MCQs with Answers

31. Kilowatt-hour is a unit of____________?

• A. Power
• B. Electric Current
• C. Energy
• D. Time
• E. None of these

Explanation: A kilowatt-hour is power multiplied by time, so it measures electrical energy consumed. It is not a unit of power, which is measured in watts or kilowatts.

32. Which of the following is mainly used for light patrol engines ?

• A. Kerosene oil
• B. Paraffin oil
• C. Heavy Fuel oil
• D. Gasoline

Explanation: Light petrol engines use gasoline, a volatile liquid fuel that ignites readily in spark-ignition engines. Heavy fuel oil is intended for large, slow-speed engines rather than light engines.

33. Which one of the following elements the drum of a Photostat machine is made up of: _________?

• A. Aluminium
• B. Selenium
• C. Barium
• D. None of these

Explanation: Photostat and photocopier drums traditionally use selenium because it is a photoconductor: its electrical conductivity changes when light falls on it. This property allows the image to be formed electrostatically.

34. Biggest award in the field of science is the __________?

• A. Noble Prize
• B. UNESCO peace prize
• C. Right livelihood prize
• D. All of these

Explanation: The Nobel Prize is widely regarded as the highest-profile international award for major scientific achievements. “Noble Prize” is a common misspelling of Nobel Prize.

35. Which is known as 'Lifeblood of industries'?

• A. Finance
• B. Transport
• C. logistic
• D. Supplies

Explanation: Finance is often called the lifeblood of industry because production, expansion, wages, and trade all require a continuous flow of capital. Transport is instead commonly described as the lifeline of trade or commerce.

36. Quality rating of deisel is called?

• A. Octane
• B. Cetane
• C. Protane
• D. Butane

Explanation: Cetane number measures the ignition quality of diesel fuel, with a higher number generally indicating easier and smoother ignition. Octane number is used for petrol or gasoline.

37. Which of the following is used to control rods in nuclear fission?

• A. Graphite
• B. Heavy Water
• C. Cadmium
• D. All of these

Explanation: Cadmium absorbs neutrons and is therefore used in control rods to regulate the chain reaction. Graphite and heavy water act mainly as moderators, slowing neutrons rather than controlling the rods.

38. Heat exchanger tubes are never made of:

• A. Plain Carbon Steel
• B. Stainless Steel
• C. Lead
• D. Copper

Explanation: Heat-exchanger tubes require adequate strength and heat-transfer performance, so materials such as carbon steel, stainless steel, and copper are commonly used. Lead is too soft and mechanically weak for ordinary heat-exchanger tubing.

39. Washing machine is working on the principle of?

• A. Photoelectric effect
• B. Electric-magnetic induction
• C. Centrifugation
• D. None of these

Explanation: A washing machine spins clothes rapidly so centrifugal action pushes water outward through the fabric and drum holes. This spin-drying process is called centrifugation.

40. The unit of home electricity energy consumption is ?

• A. Watt hour
• B. Joule hour
• C. Killowatt hour
• D. Kilo joule hour

Explanation: Domestic electricity consumption is measured in kilowatt-hours, the energy used by a 1-kilowatt appliance operating for one hour. A watt-hour is also an energy unit but is much smaller and is not the usual household billing unit.