a) Calculate the molar mass of Ethyne (C2H2). [Atomic mass: H-1 u, C-12 u]
b) Find the number of moles in 12 g of Oxygen gas? [Atomic mass: O-16 u]
c) What is the mass of 10 moles of Sodium sulphite (Na2SO3)? [Atomic mass: O-16 u, Na-23 u, S-32 u]
28. a) If Z=3, what would be the valency of the element? Also, name the element.
b) The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes 8X16 and 8X18 in the sample?
29. What are neurons? Draw a clean and labelled diagram of two neurons together.
30. Although Archana has been suffering from cold and cough, she decided to appear for her class test. Classmates seated close to her had an exposure to the infection being carried by Archana. However, only one of them actually suffered from cold and cough. Explain, what prevented rest of those classmates catching cold and cough in spite of their exposure to the infection. Write a note on infectious and non- infectious disease.
OR
A virus enters the immune system of a patient and damages its respiratory system. Answer the following:
(a) Name the disease he is suffering from.
(b) Name the pathogen and two modes of transmission of this virus.
31. Answer the followings:
a) Name the constituents of phloem tissues.
b) Write the specific function of cardiac muscle.
c) State two differences between tendons and ligaments.
d) Name the tissue that: (i) forms inner lining of our mouth. (ii) forms soft parts of leaf, stem, root and fruit.
e) Write two functions of adipose tissues.
32. a) State the law of conservation of momentum and also write its mathematical formulation.
b) A motorcar is moving with a velocity of 108km/h and it takes 4 seconds to stop after the application of brakes. Calculate the force exerted on the car if its mass is 1800kg.
33. What happens to the force of attraction between the two objects if the;
a) Mass of both the objects is tripled.
b) Distance between the objects is tripled.
c) Distance between the objects is halved.
O
Answers
a C2H2
ATOMIC MASS OF C × 2 + ATOMIC MASS OF H × 2
12×2+1×2
24+2=26u
molar mass 26g/mol.
b n=m/M
12g/16g/mol.
0.75 moles of oxygen gas
c Na2SO3
atomic mass = atomic mass of Na into 2 plus atomic mass of sulphur plus atomic mass of oxygen into 3
= 23×2+32+16×3
46+32+48
= 126 u
molar mass of 1 mole = 126g/mol.
molar mass of 10 such moles= 10×126= 1260g/mol.
28. a Z means atomic number so 3 is atomic number of the element lithium (Li)
it's valency
K,L,M
2,1
so it's valency is 1+
b. sorry bcoz in this part the x is element oxygen and I don't know proportion of its isotopes
29. The cells of nervous tissue are called nerve cells or neurons .(I have attatched image )
30. sorry don't know
31. a) sieve tubes,companion cells,phloem fibres and phloem parenchyma
b) specific function of cardiac muscles is to do rythmic contractions and relaxatiobs in heart throughout lifem
c) Tendons- 1 It connects bones to muscles
2 It has limited flexibility
3 It has great strength
4 It has very little matrix
Ligaments- 1 It connects one bone to another
2 It is very elastic
3 it has considerable strength
4 It is a fibrous tissue
d) i) Squamous epithelium
ii) Collenchyma
e) 1 it helps in storing fat below skin
2 it acts as a insulator
32. a) law of conservation of momentum states that the total momentum of two objects is unchanged or conserved by the collision
M1U1+M2U2=M1V1+M2V2
b) mass of motorcar (m)= 1800 kg
initial velocity (u)= 108km/h= 108×5/18=30m/s
final velocity v = 0 because car is stopped
time taken(t)= 4s
acceleration (a)= v-u/t
=0-30/4=-30/4=-7.5 m/s square
Force F = m×a
= 1800×-7.5
-13500 N
33. a) force of attraction/gravitation becomes 9 times of original force
b) force becomes 1/9 times of original force
c) force becomes 4 times of original force
thanku so much for questions bcoz all these chapters are coming in my final exam so while typing answers for your help it helped me also revising . it took a lot of efforts to type so pls mark as brainliest if helpful.
