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Mark ‘T’ if the statement is true and ‘F’ if it is false: (i) Nitric acid turn red litmus blue. (T/F) (ii) Sodium hydroxide turns blue litmus red. (T/F) (iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F) (iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F) (v) Tooth decay is caused by the presence of a base. (T/F)

Answer: (i) Nitric acid turn red litmus blue - False(F) Nitric acid does not turn the red litmus paper into the blue. The explanation is that the... View Article

Mark ‘T’ if the statement is true and ‘F’ if it is false. (a) Generally, non-metals react with acids. ( ) (b) Sodium is a very reactive metal. ( ) (c) Copper displaces zinc from zinc sulphate solution. ( ) (d) Coal can be drawn into wires. ( )

Answer: (a) Generally, non-metals react with acids. (False) Non-metal substances, in general, do not react with acids. When a substance reacts... View Article

Mark the correct answer. Rayon is different from synthetic fibres because (a) it has a silk-like appearance. (b) it is obtained from wood pulp. (c) its fibres can also be woven like those of natural fibres.

Answer: (b) it is obtained from wood pulp. Synthetic fibres are manmade fibres that have been prepared with chemicals. They're made up of small... View Article

Mass of one atom of oxygen is(a) 16 / 6.023 ×10²³ g (b) 32 / 6.023 ×10 ²³ g (c) 1 / 6.023× 10²³ g (d) 8u

Answer: (a) 16/6.023 × 1023 g The molecular mass of an element is defined as the sum of the masses of the elements present in the molecule.... View Article

Mention three precautions that you will take to protect yourself if an earthquake strikes when you are inside the house.

Answer: An earthquake is the shaking of the surface of Earth due to the sudden release of energy in the Earth’s crust, as a result, seismic... View Article

Meteors are not visible during the daytime. Explain the reason.

Answer: Meteors are very small objects that light as they enter the earth's atmosphere owing to friction. Because their brightness is so low in... View Article

Micro-organisms act upon the dead plants to produce (i) sand (ii) mushrooms (iii) humus (iv) wood

Answer: (iii) humus Microorganisms break down dead plants to make humus. Many microorganisms, such as algae and amoeba, decompose various dead... View Article

Morning star is the name given to (a) pole star (b) star Sirius (c) planet Jupiter (d) planet Venus

Answer: (d) planet Venus Venus is the second planet from the Sun and is the brightest planet in the solar system. It is sometimes referred to... View Article

Most liquids that conduct electricity are solutions of , and .

Answer: Most liquids that conduct electricity are solutions of acids, bases and salts. When an acid, base, or salt is dissolved in water, the... View Article

Multiply 6/13 by the reciprocal of -7/16

Answer: - 96/91 The multiplicative inverse of a number N is represented by 1/N or N-1. It is also called reciprocal, derived from the Latin word... View Article

Multiply the binomials: (2.5l – 0.5m) and (2.5l + 0.5m)

Answer: 6.25 l2 - 0.25 m2 Polynomials are algebraic expressions that consist of variables and coefficients. Polynomials are of 3 different types... View Article

Multiply the binomials: (2pq + 3q²) and (3pq – 2q²)

Answer: 6p2q2 + 5pq3 - 6q4 Polynomials are algebraic expressions that consist of variables and coefficients. Polynomials are of 3 different... View Article

Multiply the binomials: (2x + 5) and (4x – 3)

Answer: 8x² + 14x - 15 Polynomials are algebraic expressions that consist of variables and coefficients. Polynomials are of 3 different types... View Article

Multiply the binomials: (3/4 a² + 3b²) and 4( a² – 2/3 b²)

Answer: 3a4 + 10a²b² - 8b4 Polynomials are algebraic expressions that consist of variables and coefficients. Polynomials are of 3... View Article

Multiply the binomials: (a + 3b) and (x + 5)

Answer: ax + 5a + 3bx + 15b Polynomials are algebraic expressions that consist of variables and coefficients. Polynomials are of 3 different... View Article

Multiply the binomials: (y – 8) and (3y – 4)

Answer: 3y2 - 28y + 32 Polynomials are algebraic expressions that consist of variables and coefficients. Polynomials are of 3 different types... View Article

Name the effect of current responsible for the glow of the bulb in an electric circuit.

Answer: Heating effect of electric current responsible for the glow of the bulb in an electric circuit. Electric current's heating impact is... View Article

Name the part of the eye which gives colour to the eyes

Answer: Iris the part of the eye which gives colour to the eyes. The eye is an important and one of the most complex sens organs that we humans... View Article

Name the property under multiplication used in the following. -13/17 × (-2/7) = -2/7 × (-13/17)

Answer: Commutative: It states that the order of numbers in addition and multiplication does not matter. The end result will b the same. If x and... View Article

Name the property under multiplication used in the following. -19/29 × 29/-19 = 1

Answer: The multiplicative inverse of a number N is represented by 1/N or N-1. It is also called reciprocal, derived from the Latin word... View Article