Cardiff International School Dhaka (CISD)
Lost Class Make Up Assignment
Class: 8A
Subject: Chemistry
nd
Date: 22 (Sunday)-28th (Saturday) February 2015
Total Mark- 20
Instructions: All of your assignment must be done in A4 size paper. Mention your Name,
Class, Roll and Section clearly on the top sheet of your assignment.
Submission Deadline: Saturday 28th February 10.00 AM to the respective subject teacher.
The deadline is strict.
Name:.........................................................................................................................................................
Class: ......................... Roll: ........................ Sec: .................. Teacher: .............................................
Sunday-Saturday
22-28 February 2015
Lesson:
Chapter-9
The Mole
(1) Relative Atomic Mass
(2) Relative Molecular Mass
(3) The Mole
(4) Mole and Molar Mass
Task:
Read the lessons carefully mentioned above and answer the following questions.
Worksheet/Exercise:
Q1. Calculate the relative molecular mass/ relative formula mass of each of the following.
a) Ca(OH)2
b) C2H5COOCH3
c) Na2CO3.10H2O
d) Pb(NO3)2
e) (NH4)3PO4
[5]
Q2. Four nitrogen atoms have the same mass as one formula unit of XO. What is X?
[1]
Q3. A crucible contains 254 g of iodine I2. How many moles of
a) Iodine molecules and
[2]
b) Iodine atoms are there?
[2]
Q4. What is the mass of
a) 0.25 mol of oxygen gas?
[2]
b) 0.25 mol of nitrate ions (NO3-)
[2]
Q5. Calculate
a) The number of moles in 36 g of carbon.
b) The mass of 0.4 mol of hydrogen sulphide (H2S).
c) The number of atoms in 6 g of magnesium.
[6]
Text Book/Reference Book:
Chemistry Matters, Page No. 128-135, Chapter - 9
Answer keys:
Please do not see the answer keys before you do the work by yourself. Once you have done all
the work by yourself- you can match your answers with the answer options given below. In
some cases you answer might be different from what is given below but that might be correct
as well. The answer options given below for your understand only. These answer keys are the
guidelines only, you may come out with different set of right answers in line with these
options.
Q1. The relative molecular mass of an ionic compound is more accurately known as the
relative formula mass.
For example, the relative formula mass of sodium chloride (NaCl) is 23 + 35.3 = 58.5.
Q2. Mass of four nitrogen atoms is 14×4 = 56, O = 16.
Mass of element in grams
Q3. Number of moles of an element = --------------------------------------------------------Relative atomic mass of the element
Q4. 1 mol oxygen gas = 32 g, 1 mol of nitrate ions = (14+16×3) g.
Q5. 12 g of carbon = 1 mole.
34 g of hydrogen sulphide = 1 mole
24 g of magnesium contains 6×1023 atoms
Help Lines:
For any assistance, please contact
1. Coordinator:
2. Chemistry Teacher:
Naznin Nahar Nishi, 8801716310008,naznin_buet@yahoo.com
Jobaida Akther, juibmbdu@yahoo.com
3. Principal Head of School: G.M.Nizam Uddin, +88-01622181818,
gmnu302@yahoo.com