All Free Everyday Science MCQs with Answers

301. Fuse wire is made of_____________?

• A. 63% tin and 37% lead
• B. 63% lead and 37% tin
• C. 63% tin and 37% aluminum
• D. 63% lead and 37% aluminum

Explanation: Traditional solder is a low-melting alloy of about 63% tin and 37% lead, allowing it to melt and join components without melting them. Many modern solders now avoid lead for health and environmental reasons.

302. The number of electrons of a neutral atom is automatically known if one knows the?

• A. Atomic number
• B. Atomic weight
• C. Number of orbitals
• D. none

Explanation: The atomic number equals the number of protons, and a neutral atom has equal numbers of protons and electrons. Therefore, its atomic number directly gives its electron count.

303. It is a secondary plant nutrient?

• A. Nitrogen
• B. Phosphorus
• C. Sulphur
• D. none

Explanation: Sulphur is a secondary plant nutrient, along with calcium and magnesium. Nitrogen and phosphorus are classified as primary macronutrients because plants require them in larger amounts.

304. Atom is made up of____________different kinds of subatomic particles:

• A. Three
• B. Two
• C. Four
• D. None

Explanation: The standard model of an atom identifies three main subatomic particles: protons, neutrons and electrons. Protons and neutrons form the nucleus, while electrons occupy the surrounding region.

305. Phosphorus is an essential component of one of the following biological molecules:

• A. Amino acids
• B. Nucleic acids
• C. Carbohydrates
• D. None

Explanation: Phosphorus is part of the phosphate backbone of DNA and RNA, making it essential to nucleic acids. It is not a basic structural element of amino acids or carbohydrates in the same general sense.

306. Deuterium differs from Hydrogen in having:

• A. Different atomic number but same atomic weight
• B. Different atomic number and different atomic weight
• C. Same atomic number and different atomic weight
• D. None

Explanation: Isotopes have the same atomic number because they contain the same number of protons, but different atomic masses because their neutron numbers differ. Deuterium is hydrogen with one proton and one neutron.

307. The chemical name of quartz is:

• A. Silicon Dioxide
• B. Stannous Oxide
• C. Aluminium Oxide
• D. None

Explanation: Quartz is crystalline silicon dioxide, written chemically as SiO₂. The other oxides listed are different compounds and do not form ordinary quartz.

308. An instrument to detect the purity of milk is____________?

• A. Lactometer
• B. Hygrometer
• C. Manometer
• D. Sonometer

Explanation: A lactometer measures the density or specific gravity of milk, helping detect dilution or some forms of adulteration. Hygrometers measure humidity, while manometers measure pressure.

309. Water has maximum density at____________?

• A. 0°C
• B. 4°C
• C. 4° K
• D. 4.8°C

Explanation: Water reaches its greatest density at 4°C because hydrogen bonding and molecular spacing produce an unusual expansion below that temperature. This is 277 K, not 4 K.

310. In order to prevent the corrosion of iron pipes they are often coated with a layer of zinc. This process is termed as____________?

• A. Electroplating
• B. Annealing
• C. Galvanization
• D. Vulcanization

Explanation: Galvanization is the coating of iron or steel with zinc. Zinc forms a protective layer and also corrodes preferentially, helping shield the iron from rusting.