Sub- Science VIII

Chapter-4 (Materials: Metals and Non-metals)

Multiple Choice Question-
1.		The metal which is the best conductor of electricity is:
i)		gold	ii) silver		iii) copper		iv) zinc
2.		Number of naturally occurring elements:
i) 92			ii) 90		iii) 83		iv) 80
3.		Which of the following is a noble gas?
i) helium			ii) oxygen		iii) nitrogen		iv) all of these
4. All metals are solids, with the exception of:
i) aluminum			ii) graphite		iii) mercury		iv) silver
5.		A metal that is non-malleable is:
i) aluminum			ii) zinc		iii) arsenic		iv) both (ii) and (iii)
6.		A highly ductile metal is:
i) silver			ii) arsenic		iii) antimony		iv) none of these
7.		The hardest naturally occurring substance, that is a non-metal, is:
i) graphite			ii) diamond		iii) carbon		iv) none of these
	8.	The least reactive metal is:
	i)	Gold		ii) silver		iii) iron		iv) sodium
	9.	Oxides of non-metals are:
	i) acidic			ii) neutral		iii) alkaline		iv) both (i) and (ii)
	10. Firemen crawl when entering a burning building because:
	i) smoke is hot and rises					ii) it is faster to move out by crawling
	iii) both(i) and(ii)					iv) none of these

Fill in the blanks:-

1.………………………. Is an exception of non-metals with high tensile strength.

2.Iron when red hot reacts with steam to form an …………………. And ………..

3.Metals react with dilute acids to form metal …………… and ………………….

4.……………………… is the only non-metal to occur as ‘liquid’.

5.……………. And …………… are exceptions of non-metals with some degree of luster.

6.……………. Is a metal that is highly ductile.

7.………………….. and ………………… are non-ductile metals.

8.Metals react with oxygen in air to form their corresponding oxides called ……………..

9.………………….. metal has a very low melting point and melts on the plam of the hand.

Very short questions:

1 marks

1.What is metallurgy?

2.What are ores?

3.Define elements?

4.What is an alloy

5.Define oxide

6.write the name of metal which is found in liquid state at room temp. 7.what is rust chemically known.

8.what is the nature of non metallic oxide. 9.what is the nature metallic oxide.

10.name two metals which can cut with knife.

Short answer questions:	(2)marks
1.How do metals differ from non-metals in terms of:
i) physical state	ii) conductivity
iii) Lustre	iv) Malleability and ductility

2.Why are sodium and potassium stored under oil? 3. List three uses of non-metals.

4.List three uses of metals?

5.What are metalloids? Give two examples.

Answer these questions:	3 marks
1.What is aqua regia?explain with example.
2.What are displacement reactions? Give one example
3.What happens when iron reacts with air?
4.What happens when metals react with dilute acids?
5.What happens when sodium reacts with water?
Long answer questions.	(5)marks

1.Differentiate between oxides of metals and oxides of non-metals giving example.

2.What is meant by ‘Reactivity Series of Metals’? Explain.

3.What is ‘displacement reaction? Give an example.

4.Why should foodstuffs like chutney, pickles and curd not be stored on containers made of metals?

5.Write the constituents and uses of the following alloys.

(Steel ,Bronze, Brass, Stainless steel)

.

Sub- Science VIII

Chapter-2

The Microbial World

Multiple Choice Question- (1 Marks Each)

1.Bacteria are classified according to their:

	i) Shape	ii) size		iii) color		iv) none of these
2.	The first antibiotic discovered was:
	i) Penicillin	ii) Tetracycline		iii) Streptomycin		iv) Bacitracin
3.	Cholera is caused by:
	i) vibrio cholera	ii) clostridium tetani iii) salmonella typhi					iv) none of these
4.	A common bacterial disease in plants is:
	i) Citrus canker	ii) Rabies		iii) Polio		iv) All of these
5.A common food preservative is:
	i) Benzoic acid	ii) Hydrochloric acid iii) Sulphuric acid						iv) Nitric acid
6.	An edible fungi is:
	i) Mould	ii) Mushroom		iii) Algae		iv) None of these
7.	The smallest microorganism is:
	i) Algae	ii) Protozoan		iii) Bacterium		iv) Virus
8.	Algae are:
	i) Autotrophs ii) Parasites iii) Heterotrophy				iv) Saprophytes
9.	The microorganisms that play an important role in maintaining the balance of							nitrogen gas in the
	atmosphere are:
	i) Bacteria	ii) Algae	iii) Virus		iv) Protozoa

10. Which of these are added to dough to make it rise?

i) Yeast

ii) Algae

iii) garbage

iv) all of these

Fill in the blanks:- (1 Marks Each)

1.Microorganisms can be seen with the help of a ……………………..

2.Blue green algae fix ……………….. Directly from air to enhance fertility of soil.

3.Alcohol is produced with the help of ……………………….

4.Cholera is caused by …………………….

5.………………….. are non-green plants.

6.………………….. cause fermentation.

7.……………………….. and ………………………. Are diseases caused by fungi in humans.

8.A ………………….. found in the intestine of termite, help them to digest word cellulose.

9.…………………… only multiply in the body of a living organism.

10.……………….. is a fatal disease of humans as well as cattle.

Very Short Answer Question: (1 Marks Each)

1.Write the names of some diseases caused by virus.

2.What is the main ingredient of rava idlis and bhaturas.

3.What is fermentation?

4.Mention tow groups of Microorganisms on the basis of their functions?

5.Name some diseases caused by protozaans.

Short answer questions:

(2 Marks Each)

1.What are microorganisms?

2.How do microbes survive in adverse conditions?

3.How bacteria are useful to us?

4.What is virus?

5.What is fermentation? What are its utilities?

6.Write two common bacterial disease of human and write preventive measures for it?

7.What is the role of yeast in baking industry ?

8.Write sum commercial use of microorganisms?

9.What is pasteurization of milk?

10.How do microorganisms spoil food?

Answer these question		(3 Marks Each)
1.	What are major groups of microorganisms?
2.	Draw any protozoa and Label its part.
3.	What are the antibiotics? What precautions one should take while taking them?
4.	How do bacteria help in increasing soil fertility? Explain.
5.	Classify the bacteria according to their shape.
6.	What are communicable diseases ? Explain with examples.
7.	What do you mean by food poisoning ?
8.	Explain how does a vaccine work?
9.	Describe the role of blue green alae and bacteria in fertility of soil ?
10.	Give one example of each.

i) an edible fungi	ii) antibiotic obtained from fungi
iii) a parasitic protozoan	iv) nitrogen fixing bacteria
v) a bacteria residing in intestines of man	vi) what is nitrogen cycle
Long answer questions.	(5 Marks Each)

1.Draw and explain the harmfull effects of bactria with Example.

2.What are food preservatives ? Explain some common food preservatives.

3.Explain cousative microorganisms, mode of transmission and preventive measure of the human diseases like Tuberculosis, Measles, Chicken pox, Polio, Cholera, Typhoid, Hepatitis B and Maleria etc.

CLASS 9 WORKSHEET-ATOMS AND MOLECULES

1. calculate the formula mass of sodium carbonate.Na₂CO₃.10H₂O.-Ans 286u

2. Give three significance of a mole.

Ans One mole represents 6.022 x10²³ entities of a substance

       One mole of an element contains 6.022 x10²³   atoms of an element

        One mole of a substance represents one gram formula mass of the substance

3.calculate the molar mass of the following substances

(i) Ethyne  C₂H₂      12x2+1x2=26g mol^-1

 (ii) nitric acid   1+14+16x3= 63gmol^-1

_{4.calculate the number of moles present in
(i) 3.011x10}²³ _number of oxygen atoms            Ans 0.5mol

(ii) 60g of Calcium                                     Ans1.5 mol

5.Calculate the molecular masses of  (i)CH₃OH(ii) NH₃   Ans 32u  , 17 u

6. Write the postulates of Dalton atomic Theory. Explain its drawbacks

7. Write the cations and anions present in the following compounds

(i) CH₃COONa  (ii) NH₄NO₃  (iii) H ₂  (iv) NaCl

8.Write the formula of the compounds formed by the following ions

(i) Mg⁺² and S^-2   (ii) Cu⁺² and OH^-

9.How many (i) atoms (ii) molecules(iii) oxygen atoms are there in 0.5 mol of water? Ans (i) 3.011x10²³ (ii)6.022x10²³ (iii) 3.011x10²³

10 calculate the mass percent of each element of sodium in one mole of it.

Ans Mass % of Na=39.32%      Mass % of Cl = 60.68