Q.1 Which of the following is the lightest element?
Oxygen
Hydrogen
Helium
Nitrogen
Explanation - Hydrogen is the lightest element in the periodic table with an atomic number of 1 and an atomic mass of 1.008 u.
Correct answer is: Hydrogen
Q.2 Which gas is commonly known as laughing gas?
Carbon dioxide
Nitrogen dioxide
Nitrous oxide
Methane
Explanation - Nitrous oxide (N2O) is called laughing gas due to its euphoric effects when inhaled.
Correct answer is: Nitrous oxide
Q.3 The pH value of pure water at 25°C is:
6
7
8
9
Explanation - Pure water is neutral and has a pH value of 7 at 25°C.
Correct answer is: 7
Q.4 Which metal is liquid at room temperature?
Mercury
Aluminum
Sodium
Iron
Explanation - Mercury is the only metal that remains liquid at room temperature due to its unique bonding properties.
Correct answer is: Mercury
Q.5 Which of the following is a noble gas?
Nitrogen
Oxygen
Argon
Chlorine
Explanation - Argon is a noble gas found in Group 18 of the periodic table.
Correct answer is: Argon
Q.6 The atomic number of Carbon is:
4
5
6
7
Explanation - Carbon has an atomic number of 6, meaning it has 6 protons in its nucleus.
Correct answer is: 6
Q.7 Which acid is present in vinegar?
Citric acid
Sulfuric acid
Acetic acid
Hydrochloric acid
Explanation - Vinegar contains about 5–8% acetic acid by volume.
Correct answer is: Acetic acid
Q.8 The chemical symbol for gold is:
G
Ag
Au
Go
Explanation - Gold is represented by the symbol 'Au', derived from its Latin name 'Aurum'.
Correct answer is: Au
Q.9 Which of the following is not an alkali metal?
Sodium
Potassium
Calcium
Lithium
Explanation - Calcium is an alkaline earth metal, not an alkali metal.
Correct answer is: Calcium
Q.10 Which of these has the highest electronegativity?
Oxygen
Nitrogen
Fluorine
Chlorine
Explanation - Fluorine has the highest electronegativity of 3.98 on the Pauling scale.
Correct answer is: Fluorine
Q.11 Which gas is released during photosynthesis?
Carbon dioxide
Oxygen
Nitrogen
Methane
Explanation - Plants release oxygen as a by-product during photosynthesis.
Correct answer is: Oxygen
Q.12 The most abundant element in the Earth's crust is:
Oxygen
Silicon
Iron
Aluminum
Explanation - Oxygen makes up about 46% of the Earth's crust by weight.
Correct answer is: Oxygen
Q.13 The chemical formula of table salt is:
NaCl
KCl
CaCl2
MgCl2
Explanation - Table salt is composed of sodium chloride (NaCl).
Correct answer is: NaCl
Q.14 The SI unit of amount of substance is:
Mole
Gram
Kilogram
Atom
Explanation - The mole is the SI unit for the amount of substance.
Correct answer is: Mole
Q.15 Which process is used to separate salt from seawater?
Filtration
Evaporation
Distillation
Decantation
Explanation - Evaporation is used to separate dissolved salts from seawater.
Correct answer is: Evaporation
Q.16 Which is known as the 'King of Chemicals'?
Hydrochloric acid
Sulfuric acid
Nitric acid
Phosphoric acid
Explanation - Sulfuric acid is called the King of Chemicals because it is used extensively in industries.
Correct answer is: Sulfuric acid
Q.17 The study of rates of chemical reactions is called:
Thermodynamics
Stoichiometry
Kinetics
Electrochemistry
Explanation - Chemical kinetics deals with the speed and mechanism of chemical reactions.
Correct answer is: Kinetics
Q.18 What is the pH of a basic solution?
Less than 7
Exactly 7
Greater than 7
Equal to 14
Explanation - Basic solutions have a pH value greater than 7.
Correct answer is: Greater than 7
Q.19 Which element is essential for the synthesis of thyroid hormone?
Iron
Calcium
Iodine
Phosphorus
Explanation - Iodine is necessary for the production of thyroid hormones like thyroxine.
Correct answer is: Iodine
Q.20 The process of coating iron with zinc to prevent rusting is called:
Alloying
Electroplating
Galvanization
Painting
Explanation - Galvanization involves coating iron with zinc to protect it from corrosion.
Correct answer is: Galvanization
Q.21 Which gas is responsible for the greenhouse effect?
Oxygen
Carbon dioxide
Nitrogen
Hydrogen
Explanation - Carbon dioxide is a major greenhouse gas trapping heat in the atmosphere.
Correct answer is: Carbon dioxide
Q.22 Which element has the atomic number 26?
Cobalt
Nickel
Iron
Copper
Explanation - Iron has an atomic number of 26, representing the number of protons.
Correct answer is: Iron
Q.23 Which acid is found in citrus fruits?
Oxalic acid
Citric acid
Lactic acid
Acetic acid
Explanation - Citrus fruits contain citric acid, giving them their characteristic sour taste.
Correct answer is: Citric acid
Q.24 Which of these is a transition element?
Sodium
Calcium
Copper
Magnesium
Explanation - Copper is a transition element found in the d-block of the periodic table.
Correct answer is: Copper
Q.25 The main constituent of natural gas is:
Ethane
Propane
Methane
Butane
Explanation - Natural gas primarily consists of methane, a simple hydrocarbon.
Correct answer is: Methane