Answer: (c) The equation in which the number of atoms of the reactant is equal to the number of atoms of the product.

Explanation: An equation of mass value can neither be created nor destroyed, so the mass and atom value on both sides of the equation must be equal.

Answer: (a) Sodium Hydroxide + Hydrogen.

Explanation: Sodium + Water → Sodium Hydroxide + Hydrogen.

Answer: (b) White

Explanation: The color of silver chloride is white, which turns gray from silver when sunlight.

Answer: (c) Smell and taste.

Explanation: When fats and oils are oxidized it becomes rancid and their smell and taste change.

Answer: (b) Red to blue

Explanation: The bases change the litmus paper from red to blue, while acids change the litmus paper from blue to red.

Answer: (b) Odor

Explanation: Olfactory indicators are substances that give information about acids and bases by changing their odor.

Answer: (c) Salt + Water

Explanation: Metal oxide + Acid → Salt + Water

Answer: (c) Plaster of Paris

Explanation: On heating the gypsum at 373K, it converts into Calcium Sulphate Hemihydrate (CaSO₄.1/2H₂O). It is also known as plaster of Paris, which is used in cement industries and sculpture making.

Answer: (d) Diamond

Explanation: Diamond is not a lustrous metal. It has no shining of its own. It only reflects the light falling on it.

Answer: (a) Mercury

Explanation: All metals, except mercury, are solid at room temperature. It occurs in liquid form at room temperature because its melting point is low.

Answer: (b) Potassium

Explanation: Potassium is the most reactive metal due to its position in the reactive series.

Answer: (c) Gold

Explanation: Gold is the most non-reactive metal due to its position in the reactive series.

Answer: (d) Propane

Explanation: Propane has three carbon atoms and eight hydrogen atoms, so its chemical formula is C₃H₈.

Answer: (a) Oic acid

Explanation: The chemical formula of a carboxylic acid is R-COOH. In which the carbon atom is a double bond with an oxygen atom and a single bond with a hydroxide molecule. Therefore, it takes the prefix oic acid.

Answer: (b) CH₃COOCH₂CH₃

Explanation: The ester compound is a mixture of alcohol and carboxylic acids, and its chemical formula is CH₃COOCH₂CH₃.

Answer: (a) Micelles

Explanation: Soap is a long chain of hydrocarbon. One end is hydrophilic, which connects with a water molecule. One is hydrophobic, which connects with dirt and oil particle and forms a structure called micelles.

Answer: (d) Mass

Explanation: According to Mendeleev’s periodic table, elements’ chemical properties are functions of their mass, so they have arranged the elements according to their mass.

Answer: (b) Hydrogen

Explanation: Hydrogen has one electron on its outer cell, so it belongs to the seventh and first group. Therefore, hydrogen could not find any place in the Mendeleev periodic table.

Answer: (a) 18

Explanation: There are eighteen groups and seven periods in the modern periodic table.

Answer: (a) Halogen

Explanation: Chlorine has seven outermost electrons and has a valency of one, so it belongs to the 17th group i.e., the halogen group.

Answer: (c) Photosynthesis.

Explanation: Plants perform photosynthesis in which they get nutrition. In this process, plants are formed by synthesizing water and carbon dioxide in the presence of glucose and water made from sunlight, which gives them energy.

Answer: (d) Salivary

Explanation: The salivary gland is present in the human mouth, which is secretive saliva. It is slightly acidic in nature, which helps in killing the germs that come with food and makes the food fluffy so that it can be easily digested.

Answer: (d) Alveoli

Explanation: Alveoli is present in the human’s lungs, in which the exchange of gases takes place. In the human lungs, carbon-di-oxide is taken up by alveoli and releases oxygen into human blood.

Answer: (b) Nephron

Explanation: The basic unit of the kidney is the nephron. It consists of glomerulus, bowman’s capsule, renal arteries. It helps in expelling water and minerals from the human body.

Answer: (a) Neuron

Explanation: The nervous system’s basic unit is the neuron by which instructions are transferred from the brain to other parts of the body.

Answer: (c) Central nervous system

Explanation: The full form of CNS is the central nervous system. The central nervous system has two main parts: the brain and spinal cord.

Answer: (c) Three

Explanation: The three main parts of the human middle brain are the colliculi, tegmentum, and cerebral peduncles. This part is present at the top of the human brain, and it helps in balancing the body.

Answer: (b) Testosterone

Explanation: Testosterone is secreted by the gonads in the male reproductive system, which helps in the creation of sperm.

Answer: (a) Follicle Stimulating Hormone

Explanation: The full form of the FSH is Follicle Stimulating Hormone. It is secreted in females and helps in the menstrual cycle. It controls the growth of the egg.

Answer: (c) Budding

Explanation: Hydra is reproduced by budding. A small bud is produced in the body of hydra. When this bud matures, it separates from Hydra’s body.

Answer: (d) Vegetative propagation

Explanation: The name of the process occurring in the Bryophyllum plant is vegetative propagation. In this process, notches are formed on the margins of its leaves. When they mature, they are separated from the leaves of the plant.

Answer: (b) Stigma

Explanation: Stigma is the reproductive organ of a pollinating female plant. It stimulates the formation of the tube in style through which pollen particles flow and reach the ovary.

Answer: (b) 23 pairs

Explanation: A human has 23 pairs of chromosomes. One pair has the sex chromosome that determines the sex of the human body, and the other 22 pairs are autosomes.

Answer: (c) Seven

Explanation: Mandel experiment on the pea plant in which he finds seven-character which are different in one sense. After crossing the plant of a different character, he gives the theory of heredity.

Answer: (c) Charles Darwin

Explanation: The father of evolution is Charles Darwin. Charles Darwin was a British naturalist who proposed the theory of biological evolution by natural selection.

Answer: (a) The organs whose work are the same but structure is different.

Explanation: Analogous organs are those organs which work are the same, but their structure is different-for example, both the bat’s hand and the bird’s hand fly, but their internal structures are different.

Answer: (b) Diverging mirror

Explanation: Convex mirror is also known as the diverging mirror because it diverges the ray of light falling on it.

Answer: (a) R = 2F

Explanation: The radius of curvature is twice the focal length of the mirror. Therefore, option a is the correct answer.

Answer: (d) Diopter

Explanation: The SI unit of the lens is diopter that is equal to the reciprocal of the focal length of the mirror (P = 1 / F)

Answer: (a) O₃

Explanation: Ozone is made by the addition of O₂ with O. Therefore, the chemical formula of the ozone is O₃.

Answer: (a) Distant object

Explanation: A person suffering from myopia is unable to see a distant object because his cornea is enlarged, due to which image is not formed at the retina.

Answer: (c) Seven

Explanation: The rainbow has seven colors (Violet, Indigo, Blue, Green, Yellow, Orange, Red)

Answer: (d) Retina

Explanation: Images are formed on the retina in the eye. Pictures are inverted on the retina. The retina sends images to the brain using optical nerves.

Answer: (b) N = speed of light (in air)/speed of light (in medium)

Explanation: Absolute refractive index is equal to the ratio of the speed of light in air (c) and speed of light in that medium for which we calculate the refractive index (v). The formula of absolute refractive index n = c/v.

Where,

n = Absolute refractive index

c = Speed of light in air

v = Speed of light in medium

Answer: (a) V = IR

Explanation: According to ohm’s law, electric current through a current-carrying conductor is directly proportional to the applied voltage to the conductor.

Answer: (c) Volt

Explanation: The SI unit of potential is volt. A volt is defined as the energy used in bringing a unit charge from infinity to that point in an electric field.

Answer: (d) Current

Explanation: According to Kirchhoff’s law, the current in a loop is the same throughout the loop. When we apply resistance in series, the current is constant across all resistors.

Answer: (c) Electromagnetic induction

Explanation: Electric generator is work on the basic principle of electromagnetic induction. It says that “In a magnetic field when current across the wire is changed then a force is applied on that wire in the direction according to Fleming’s right-hand rule”.

Answer: (d) Nostrils → pharynx → larynx → trachea → alveoli

Explanation: Nostrils → pharynx → larynx → trachea → alveoli. The alveoli provide a surface where gases can be exchanged.

Answer: (a) Methane

Explanation: Biogas plants produce methane, carbon dioxide, and hydrogen sulphide, in which methane is produced in large quantities. It serves as a fuel and is used domestically for energy. In this way, it acts as a traditional source of energy.