CLASS 10
PERIODIC CLASSIFICATION OF ELEMENTS
LESSON NOTES

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class 9 holiday homework
(refer the blog's of your respective teachers)

Maths - worksheet in  the blog  

science- worksheet in the blog 

Hindi- Blog

Social science- Group activity on Food security
Geography- Choose any one topic from the following and write about it.( Pictures ,Map ,Causes Prevention, effects)
    Tsunami
     Drought
      Land slides

English-

 1.Article on the topic (200 words)
Sedentary lifestyles and unhealthy eating habits leads to obesity

2Story writing (150- 250 words)
.ENDING. WITH... HE TOUCHED HIS GURU'S FEET AND ASKED FOR AN APOLOGY
 BEGINNING WITH...AS I OPENED THE WINDOW i SAW...

3LETTER-
 You recently upgraded the band of your net.However the speed is quite low and it is difficult to load websites.You have complained to customer sevices, but they are extremely  unhelpful.Write a letter to General Manager  World Tel  internet Service provider complaining about  the service

lesson -4 CLASS 10
CARBON AND ITS COMPOUNDS LESSON NOTES
ETHANOL, ETHANOIC ACID AND SOAPS AND DETERGENTS
PAGE noARE GIVEN BELOW

CLASS-9 HOLIDAY H W
LESSON-3 ATOMS AND MOLECULES(A-4 SIZE PAPER)

1	What is an atom?
2	How many atoms are present in one molecule of ozone?
3	Define the law of constant proportion.
4	What is the ratio between masses of (a) hydrogen and oxygen in H2O (b) nitrogen and hydrogen in NH3? [Atomic mass of H = 1 u, O = 16 u, N = 14 u]
5	What is the ratio between masses of carbon and oxygen in CO2? [Atomic mass of C = 12 u, O = 16 u]
6	As per the law of definite proportions carbon and oxygen combine in a ratio of 3 : 8. Compute the mass of oxygen gas that would be required to react completely with 6 g carbon.
7	Name the anion and cation which constitute the molecule of magnesium oxide.
8	Name the international organisation which approves the name given to the elements.
9	The oxide of aluminium has a chemical formula Al2O3. State the valency of Al.
10	Write the names of the following compounds: (a) Al2(SO4)3 (b) NH4OH
11	What is the formula of ammonium chloride?

12	(a) Define atomic mass unit. (b) Hydrogen and oxygen combine in the ratio 1: 8 by mass to form water. What mass of oxygen gas would be required to react completely with 4 g of hydrogen gas?
13	(a) Give one word for the following: (i) Positively charged ion (ii) A group of atoms carrying a charge. (b) Mention any two important rules for writing a chemical formula.

14	(a) How would you differentiate between a molecule of an element and a molecule of a compound? Write one example of each type. (b) Write the chemical formula of baking soda.
15	Define atomicity. Give an example of each of monoatomic, diatomic, tetra-atomic and polyatomic molecules.
16	Classify the following compounds as diatomic, triatomic and polyatomic molecules: HCl, H2, H2O and NH3.
17	How will you prove experimentally the law of conservation of mass?
18	(a) When 5 g of calcium is burnt in 2 g of oxygen then 7 g of calcium oxide is produced. What mass of calcium oxide will be produced when 5 g of calcium is burnt in 20 g of oxygen. Which law of chemical combination will govern your answer? State the law. (b) Write the chemical formula of calcium oxide.
19	(i) Write the full form of IUPAC. (ii) Hydrogen and oxygen combine in the ratio of 1 : 8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?
20	Write the formulae of (a) Magnesium hydroxide (b) Hydrogen sulphide (c) Potassium chloride (d) Calcium oxide (e) Barium chloride (f) Sodium carbonate
21	An element ‘X’ forms an oxide with formula X2O3 (a) State the valency of X. (b) Write the formula of (i) chloride of X, (ii) sulphate of X.
22	Using criss-cross method, write the chemical formulae of copper chloride, calcium sulphate and sodium phosphate.
23	(a) What are polyatomic ions? (b) Write the formulae and names of the compounds formed by combination of (i) Fe3+ and SO42– (ii) NH4+ and CO32–
24	Write the formulae of: (a) Sodium chloride (b) Aluminium oxide (c) Ammonium sulphate
25	(a) Define polyatomic ion. (b) Write the name of the compound (NH4)2SO4 and mention the ions present in it.

REVISION WORKSHEET-CLASS 8
  FORCE AND PRESSURE

ANSWER OF QUESTION 28

The woman wearing sandals with flat soles will feel more comfortable while walking on the sandy beach. The flat soles have larger area compared to the sandals with pointed heels. Since the two women are of the same weight, they will apply same force on the ground. Therefore, the pressure exerted by the pointed heels will be more compared to that with sandals having flat soles. As a result the pointed heel sandals will sink more in the sand than the flat sole sandals. Hence, walking with flat sole sandals will be more comfortable.

RREVISION WORKSHEET

8 METALS AND NONMETALS

class 8 revision worksheet
COMBUSTION AND FLAME