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Q1
A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plants bearing white flowers. What will be the result in F₁ progeny?
Marks:1
Answer:

The result in F₁ progeny will be a violet flower because in this case, violet colour is the dominant character.

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Q2
Write the energy conversion that takes place in a hydropower plant.
Marks:1
Answer:

In hydropower plant, when the water stored at a certain height is released, its potential energy gets converted into kinetic energy. This kinetic energy is used to rotate the turbine.

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Q3
A compound 'X' on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound 'Y'. 'X' also reacts with sodium metal to evolve a colorless gas 'Z'. Identify 'X', 'Y' and 'Z'. Write the equation of the chemical reaction of formation of 'Y' and also write the role of sulphuric acid in the reaction.
Marks:2
Answer:

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Q4
(a) Name one gustatory receptor and one olfactory receptor present in human beings.

(b) Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.
Marks:2
Answer:

(a) Gustatory receptor: Tongue

Olfactory receptor: Nose
(b)

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Q5
If the image formed by a spherical mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a labelled ray diagram to support your answer.
Marks:2
Answer:

A convex mirror always forms an erect and diminished imageirrespective of the position of the object placed in front of it.

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Q6
Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity.
Marks:3
Answer:

A reaction in which a compound is broken into two or more simpler substances is known as decomposition reaction.

(i)Thermal decomposition:On heating calcium carbonate decomposes into calcium oxide and carbon dioxide gas.

(ii)Electrolytic decomposition:When an electric current is passed through water, it decomposes to produce hydrogen and oxygen gas.

(iii)Photochemical decomposition: When silver chloride is exposed to light, it decomposes to form silver metal and chlorine gas.

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Q7
2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.
Marks:3
Answer:

Test for hydrogen:When a burning splinter brought near to the mouth of the test tube the gas starts burning with a ‘pop’ sound which confirms that the evolved gas is hydrogen.

Reaction of zinc with dilute sulphuric acid:When zinc reacts with dil. sulphuric acid it forms hydrogen gas.

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Q8
The pH of a salt used to make tasty and crispy pakoras is 14. Identify the salt and write a chemical equation for its formation. List its two uses.
Marks:3
Answer:

The salt used for making tasty and crispy pakoras is sodium hydrogen carbonate. Its chemical formula is NaHCO₃.

(i) It is used as an antacid to remove acidity of the stomach.

(ii) It is also used in fire extinguishers.

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Q9
(a) Why are most carbon compounds poor conductors of electricity?

(b) Write the name and structure of a saturated compound in which the carbon atoms are arranged in a ring. Give the number of single bonds present in this compound.
Marks:3
Answer:

(a) Most of the carbon compounds are covalent compounds. Covalent bond is formed by the mutual sharing of the electrons between the atoms and therefore, no charged particles or ions are formed which can conduct of the electricity. Therefore, carbon compounds are poor conductors of electricity.

(b) Cyclohexane is a saturated cyclic hydrocarbon having 6 carbon atoms. It has 18 single bonds present in it.

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Q10

Name the hormones secreted by the following endocrine glands and specify one function of each:

(a) Thyroid (b) Pituitary (c) Pancreas

Marks:3

Answer:

Endocrine gland	Hormones	Function
Thyroid	Thyroxine	It regulates the metabolism of proteins, fats and carbohydrates in the body
Pituitary	Growth hormone	It regulates the growth and development of muscles and bones
	Prolactin hormone	It regulates the functions of mammary gland in females
	Vasopressin hormone	It maintains water and electrolyte balance in the body
	Oxytocin hormone	It is responsible for signaling contractions of the womb during labor and regulates milk ejection during lactation
Pancreas	Glucagon	It helps in increasing blood sugar level of the body
Pancreas	Insulin	It helps in maintaining blood sugar level.