10th Science Assignment 2 Answer key - July 2021

Assignment

Class-10 Subject:   SCIENCE 2nd Assignment Answer

UNIT – VII- Atoms and Molecules

Part – A

I.One Mark Questions

1. Number of electrons, protons and neutrons present in 17Cl35, 17Cl37 is…………….

a) 17e ̄ , 17p+, 17n

17e ̄ , 17p+, 19n

b) 18e ̄ , 18p+, 17n

17e ̄ , 20p+, 19n

c) 17e ̄ , 17p+, 18n

17e ̄ , 17p+, 20n

d) 18e ̄ , 17p+, 18n

20e ̄ , 20p+, 17n

Answer:- a) 17e ̄ , 17p+, 17n

17e ̄ , 17p+, 19n

2. Isobars are defined as………..

a) Elements show same atomic number with different mass number

b) Elements show same mass number with different atomic number

c) Elements show same valency

d) None of these

Answer:- b) Elements show same mass number with different atomic number

3.The Atomicity of Glucose molecule is………………..

a) 6

b) 12

c)24

d) 18

Answer:- c)24

4.The mass of 5 moles of sodium is……….

a) 46g

b) 34g

c) 105g

d) 115g

Answer:- d) 115g

5.Number of atoms present in 3 moles of iron is——–

a) 6.023 x 1023

b) 18.069 x 1023

c) 12.046 x 1023

d) None

Answer:- b) 18.069 x 1023

Part – B

II. Short Answer.

6.Define : Relative atomic mass

7.Give any two examples for heteroatomic molecules

• HI, HCl, CO, HBr, HF.

8.Calculate the number of moles in 46 g of Sodium?

• Formula to calculate the no. of moles:
• No of moles = known mass of a substance/ molar mass of the substance.
• No. of moles of Na= 46 / 23

                            = 2 moles

• So in 46 grams, 2 moles of Na are present.

9.Calculate the mass of the 5×1023 molecules of Glucose.

10.Calculate the number of molecules in 11.2 litre of CO2 at S.T.P.

Part – C

III. Write in detail.

1.Give the salient features of “Modern Atomic Theory”.

• The salient features of “Modem atomic theory” are,

• An atom is no longer indivisible.

• Atoms of the same element may have different atomic mass.

• Atoms of different elements may have the same atomic masses.

• Atoms of one element can be transmuted into atoms of other elements. In other words, an atom is no longer indestructible.

• Atoms may not always combine in a simple whole-number ratio.

• Atom is the smallest particle that takes part in a chemical reaction.

• The mass of an atom can be converted into energy [E = mc2].

Assignment

Class-10 Subject:SCIENCE

UNIT – XII

Plant Anatomy and Plant Physiology

Part – A

I. OneMark Questions

1.Who is the father of plant anatomy?

a) Sachs

b) Nehemiah Grew

c) Melvin Calvin

d) C.N.R.Rao

Answer : b) Nehemiah Grew

2.The group of cells which are similar or dissimilar in structure and origin that perform similar function is called

a) Organ System

b) Vascular Bundles

c) Tissues

d) Pericycle

Answer : c) Tissues

3.The pores present in Epidermis are called

a) Stomata

b) Cuticle

c) Trichome

d) Stele

Answer : a) Stomata

4.Xylem and Phloem are present in different radii of ———-

a) root

b) stem

c) leaf

d) flower

Answer : a) root (Xylem and phloem are arranged in an alternate matter or different radii are called Radial vascular bundle. Eg: roots)

5.If xylem and phloem lie on the same radii that vascular bundle is…..

a) radial bundle

b) conjoint bundle

c) concentric and amphivasal

d) amphicribral

Answer : b) conjoint bundle

Part – B

II. Short Answer.

1.What are tissues?

2.Classify the types of plant tissues.

• Merismatic tissue and permanent tissue

3.What are the functions of Dermal or Epidremal tissue system?

• Epidermis protects the inner tissues.
• Stomata helps in transpiration.
• Root hairs help in absorption of water and minerals.

4.Write a short note about vascular bundle of Dicot root.

5.What is Radial vascular bundle? Give example.

• Radial vascular bundle: Xylem and phloem are arranged in an alternate matter or different radii are called Radial vascular bundles. Eg: roots

Part – C

III. Write in detail.

6.a)Differentiate the following

Monocot root and Dicot root

Monocot Root

• Xylem is a poly arch

• Pith is usually large at the center

• Conjunctive tissue is made up of sclerenchyma

• There is no secondary growth

Dicot Root

• Xylem is usually tetrarch

• Pith is usually absent

• Conjunctive tissue is made up of parenchyma

• Secondary growth is generally present

b) Draw a neat labelled diagram of Radial vascular bundle