The gas used in a refrigerator to cool water is___________?
A. Nitrogen
B. Carbon dioxide
C. Methane
D. Tetrafluoroethane
Explanation: The gas used in a refrigerator to cool water is Tetrafluoroethane. This gas, also known as R-134a, is commonly used as a refrigerant in modern refrigeration systems. It has good thermodynamic properties for cooling and is considered environmentally friendly compared to older refrigerants such as chlorofluorocarbons (CFCs).
The average adult has a blood volume of about __________ liters.
A. 4
B. 5
C. 6
D. 7
Explanation: The average adult has a blood volume of about 5 liters.
The Sun is a __________?
A. Star
B. Planet
C. Asteroid
D. Meteor
Explanation: The Sun is a massive, luminous sphere of hot plasma, primarily composed of hydrogen and helium. It is the central and most important star in our solar system, providing light, heat, and energy to sustain life on Earth
The most abundant element in the Earth’s crust is __________?
A. Oxygen
B. Hydrogen
C. Carbon Dioxide
D. Silicon
Explanation: The most abundant element in the Earth’s crust is oxygen. Oxygen makes up about 46% of the Earth’s crust by weight. It is a vital element for supporting life and is found in various compounds, such as silicates, oxides, and carbonates. Oxygen is also a major component of the Earth’s atmosphere, making up approximately 21% of the air we breathe.
Each day human body breathe in __________ liters of air.
A. 5,000 to 10,000
B. 10,000 to 15,000
C. 15,000 to 20,000
D. 20,000 to 25,000
Explanation: Each day, the human body breathes in approximately 15,000 to 20,000 liters of air. Breathing is an essential process that allows oxygen to enter the body and carbon dioxide to be expelled. The exact volume of air breathed in may vary depending on factors such as activity level, respiratory rate, and individual characteristics.
Deficiency of Vitamin-D results in __________?
A. night blindness
B. rickets
C. scurvy
D. hair fall
Explanation: Deficiency of Vitamin-D results in rickets. Vitamin-D plays a crucial role in the absorption of calcium and phosphorus, which are essential for bone health and development. Insufficient levels of Vitamin-D can lead to impaired bone growth and mineralization, resulting in soft and weak bones, a condition known as rickets.
The most abundant element in the universe is __________
A. Oxygen
B. Hydrogen
C. Carbon Dioxide
D. Silicon
Explanation: The most abundant element in the universe is hydrogen. Hydrogen makes up about 75% of the elemental mass in the universe and is found in vast quantities in stars and interstellar clouds. It is the primary building block of the universe and plays a crucial role in the formation and evolution of galaxies, stars, and other celestial objects.
The SI unit of “pressure” is _________.
A. pascal
B. joule
C. tesla
D. henry
Explanation: The SI unit of “pressure” is pascal (Pa). Pascal is the derived unit of pressure in the International System of Units (SI) and is defined as one newton per square meter (N/m²). It is named after the French mathematician and physicist Blaise Pascal.
The most densest substance on the Earth is __________.
A. Platinum
B. Copper
C. Steel
D. Osmium
Explanation: The most dense substance on Earth is osmium (D). Osmium is a rare and extremely dense metal with a density of approximately 22.6 grams per cubic centimeter (g/cm³). It is even denser than platinum, which is known for its density as well. Osmium is often used in certain specialized applications, such as in high-precision instruments and electrical contacts.
A camera uses a __________ to form an image.
A. convex lens
B. concave lens
C. condenser lens
D. none of these
Explanation: A camera uses a convex lens (A) to form an image. The convex lens converges light rays and focuses them onto the camera’s image sensor or film, creating a sharp and clear image. The lens helps adjust the focal length and capture the desired field of view for photography or videography.