science
In a redox reaction, what is the process called when a substance gains electrons?
- Oxidation
- Reduction
- Hydrolysis
- Neutralization
Explanation:
- Reduction is defined as the gain of electrons by a substance.
- Oxidation is the loss of electrons.
- Hydrolysis is a reaction with water.
- Neutralization is an acid-base reaction.
Which of the following is a common oxidizing agent?
- Sodium Sulphite
- Hydrochloric Acid
- Potassium Permanganate
- Oxalic Acid
Explanation:
- Potassium Permanganate (KMnO₄) is a strong oxidizing agent used in titrations.
- Sodium Sulphite is a reducing agent.
- Hydrochloric acid is not typically an oxidizing agent.
- Oxalic acid is a reducing agent.
What happens to the oxidation number of an element during oxidation?
- It decreases
- It remains constant
- It increases
- It becomes zero
Explanation:
- The oxidation number increases when an element loses electrons (oxidation).
- It decreases during reduction (gain of electrons).
- It remains constant if no redox occurs.
- It becomes zero for elements in their free state.
In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, which substance is reduced?
- Zinc (Zn)
- Zinc Sulphate (ZnSO₄)
- Copper ions (Cu²⁺)
- Sulphate ions (SO₄²⁻)
Explanation:
- Copper ions (Cu²⁺) gain electrons to become Cu metal, so they are reduced.
- Zinc (Zn) loses electrons and is oxidized.
- Zinc Sulphate is a product of oxidation.
- Sulphate ions are spectators and do not change.
Rusting of iron is an example of what type of reaction?
- Displacement reaction
- Combination reaction
- Redox reaction
- Double displacement reaction
Explanation:
- Rusting is a redox reaction where iron is oxidized and oxygen is reduced.
- It is not a simple displacement or combination.
- It is not a double displacement as no ions are just swapping.
Which device converts chemical energy into electrical energy through redox reactions?
- Electric motor
- Generator
- Galvanic cell
- Electrolytic cell
Explanation:
- A Galvanic (or Voltaic) cell uses spontaneous redox reactions to produce electricity.
- An electrolytic cell uses electricity to drive a non-spontaneous reaction.
- An electric motor converts electrical to mechanical energy.
- A generator converts mechanical to electrical energy.
What is the oxidation state of sulfur in H₂SO₄?
- +2
- +4
- +6
- -2
Explanation:
- In H₂SO₄, H is +1 (each), O is -2 (each). So, 2(+1) + S + 4(-2) = 0. Solving gives S = +6.
- +2 is for sulphites like SO₂.
- +4 is for sulphites like SO₃²⁻.
- -2 is for sulphides like H₂S.
Which of these is NOT a reducing agent?
- Carbon monoxide (CO)
- Sulphur dioxide (SO₂)
- Hydrogen (H₂)
- Ozone (O₃)
Explanation:
- Ozone (O₃) is a powerful oxidizing agent, not a reducing agent.
- Carbon monoxide (CO) reduces metal oxides to metals.
- Sulphur dioxide (SO₂) acts as a reducing agent in many reactions.
- Hydrogen (H₂) reduces metal oxides and unsaturated compounds.
The process of coating a thin layer of zinc on iron to prevent rusting is called?
- Tinning
- Galvanization
- Anodization
- Passivation
Explanation:
- Galvanization is the process of applying a protective zinc coating to iron or steel.
- Tinning is coating with tin.
- Anodization is for aluminium.
- Passivation is making a material passive (less reactive).
Which part of a neuron receives signals from other neurons?
- Axon
- Dendrite
- Node of Ranvier
- Myelin Sheath
Explanation:
- Dendrites are the branched projections of a neuron that receive electrical signals.
- The axon transmits signals away from the cell body.
- The Node of Ranvier are gaps in the myelin sheath.
- The Myelin Sheath insulates the axon.
The gap between two neurons where communication occurs is called a?
- Junction
- Cleft
- Synapse
- Gateway
Explanation:
- A Synapse is the junction between two neurons where neurotransmitters are released.
- It is a specific term, not just a general junction or cleft.
What is the function of the myelin sheath?
- To produce neurotransmitters
- To receive stimuli
- To insulate the axon and speed up signal transmission
- To connect neurons to muscles
Explanation:
- The Myelin Sheath is a fatty layer that insulates axons, enabling rapid transmission of nerve impulses.
- Neurotransmitters are produced in the neuron cell body.
- Dendrites receive stimuli.
- Neuromuscular junctions connect neurons to muscles.
The gaps in the myelin sheath along an axon are known as?
- Synaptic clefts
- Axon terminals
- Nodes of Ranvier
- Dendritic gaps
Explanation:
- Nodes of Ranvier are the periodic gaps in the myelin sheath where action potentials are regenerated.
- The synaptic cleft is the gap between neurons at a synapse.
- Axon terminals are the ends of axons that release neurotransmitters.
What is the basic unit of the nervous system?
- Synapse
- Brain
- Neuron
- Spinal cord
Explanation:
- The Neuron (or nerve cell) is the fundamental structural and functional unit of the nervous system.
- The synapse is a structure between neurons.
- The brain and spinal cord are organs made up of neurons.
Which vitamin is essential for the synthesis of prothrombin?
- Vitamin A
- Vitamin C
- Vitamin K
- Vitamin D
Explanation:
- Vitamin K is essential for the liver to synthesize prothrombin and other clotting factors.
- Vitamin A is for vision.
- Vitamin C is for collagen.
- Vitamin D is for calcium absorption.
The ‘Pacemaker’ of the heart is the?
- AV Node
- Bundle of His
- SA Node
- Purkinje fibers
Explanation:
- The Sinoatrial (SA) Node generates the electrical impulses that initiate heartbeats, acting as the natural pacemaker.
- The AV node delays the impulse.
- The Bundle of His and Purkinje fibers conduct the impulse through the ventricles.
Which gland in the human body is known as the ‘master gland’?
- Thyroid gland
- Adrenal gland
- Pituitary gland
- Pineal gland
Explanation:
- The Pituitary Gland is called the ‘master gland’ because it controls other endocrine glands.
- The thyroid regulates metabolism.
- The adrenal gland produces stress hormones.
- The pineal gland produces melatonin.
Photosynthesis is a process of?
- Oxidation
- Reduction
- Neutralization
- Decomposition
Explanation:
- In photosynthesis, carbon dioxide is reduced to form glucose.
- Water is oxidized to oxygen.
- It is not a neutralization or simple decomposition reaction.
Which of the following is a greenhouse gas?
- Oxygen
- Nitrogen
- Methane
- Argon
Explanation:
- Methane (CH₄) is a potent greenhouse gas that traps heat in the atmosphere.
- Oxygen and Nitrogen are not greenhouse gases.
- Argon is an inert gas and not a significant greenhouse gas.
The SI unit of electric current is?
- Volt
- Ohm
- Ampere
- Watt
Explanation:
- The Ampere (A) is the SI base unit of electric current.
- Volt is the unit of potential difference.
- Ohm is the unit of resistance.
- Watt is the unit of power.
Which metal is liquid at room temperature?
- Sodium
- Aluminium
- Mercury
- Copper
Explanation:
- Mercury (Hg) is the only metal that is in a liquid state at standard room temperature.
- Sodium, Aluminium, and Copper are all solids at room temperature.
Sound waves are which type of waves?
- Transverse waves
- Longitudinal waves
- Electromagnetic waves
- Polarized waves
Explanation:
- Sound waves are Longitudinal waves, meaning the particles vibrate parallel to the direction of wave propagation.
- Light and radio are transverse electromagnetic waves.
The hardest natural substance on Earth is?
- Gold
- Platinum
- Diamond
- Iron
Explanation:
- Diamond (a form of carbon) is the hardest known natural material on the Mohs scale.
- Gold and Platinum are soft metals.
- Iron is much softer than diamond.
Which gas is produced during photosynthesis?
- Carbon Dioxide
- Nitrogen
- Oxygen
- Hydrogen
Explanation:
- Oxygen (O₂) is released as a byproduct when plants split water molecules during photosynthesis.
- Carbon Dioxide is consumed, not produced.
- Nitrogen and Hydrogen are not direct products.