Calcium Floats Over Water During the Reaction with Water. Give Reason. - Science and Technology 2

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Calcium floats over water during the reaction with water. Give reason.  



1. Calcium reacts with waterless vigorously so that the heat evolved is not sufficient for the hydrogen formed, to catch fire.

2. Instead, calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the water calcium

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2014-2015 (July)



.................... liberated when acetic acid reacts with sodium metal.
(a) Hydrogen
(b) Chlorine
(c) Oxygen
(d) Nitrogen

A solution of CuSO4 in water is .................... in colour.
(a) Pink
(b) Blue
(c) Colourless
(d) Green

Metal A has electronic configuration (2, 8, 1) and metal B has (2, 8, 8, 2). Which is more reactive? Why? Identify these metals.

_________ solution is blue in colour.
(a) CuSO4
(b) FeSO4
(c) ZnSO4
(d) Al2(SO4)3

Iron is
(a) More reactive than zinc
(b) More reactive than aluminium
(c) Less reactive than copper
(d) Less reactive than aluminium

Name the following:
Metals which forms an amphoteric oxide.

‘E’ is an element which reacts with oxygen to form an oxide E2O. An aqueous solution of E2O turns red litmus blue, so:
i. What is the nature of oxide E2O ?
ii. Write the name of element ‘E’.

The solution of Aluminium sulphate in water is .....................

(a) Green

(b) Colourless

(c) Pink

(d) Blue

The reaction of an iron nail with copper sulphate solution is ........... reaction.

(a) Combination

(b) Displacement

(c) Double displacement

(d) Decomposition

A solution of _________________ in water is green in colour.

(a) CuSO4
(b) FeSO4
(c) ZnSO4
(d) Al2(SO4)3

Explain the following reaction with the help of a balanced chemical equation:
Magnesium reacts with hot water.

Write equation for the reaction of sodium with oxygen.

What will happen if a strip of zinc is immersed in a solution of copper sulphate?

How do metals react with hydrogen? Explain with an example.

What happens when a rod of zinc metal is dipped into a solution of copper sulphate? Give chemical equation of the reaction involved.

What is the action of water on aluminium ? Write equation of the chemical reaction involved.

What happens when a metal reacts with dilute hydrochloric acid? Explain with the help of an example.

Name one metal which displaces copper from copper sulphate solution and one which does not.

The elements whose oxides can turn litmus solution blue are:
(a) carbon and sulphur
(b) sodium and carbon
(c) potassium and magnesium
(d) magnesium and sulphur

A zinc plate was kept in a glass container having CuSO4 solution. On examining it was found that the blue colour of the solution is getting lighter and lighter. After a few days, when the zinc plate was taken out of the solution, a number of small holes were noticed in it. State the reason and give chemical equation of the reaction involved.

Choose the correct alternative and rewrite the following:

Reaction of iron nails whith copper sulphate solution is an example of _____________________

Choose the correct alternative and rewrite the following:

Which of the following is lue in colour?

Write the chemical equation of the above process.

Answer the following question:
An element X on reacting with oxygen forms an oxide X2O. This oxide dissolves in water and turns red litmus blue. State whether element X is metal or a non - metal. Explain with a proper example. 

The substance that will be flattened on beating with a hammer is

Metals are generally hard. Which of the following metals is an exception and can be cut with a knife?

Which of the following property is not responsible for copper to be used as electrical conduction wires?

Find the odd one out:

Tungsten wire is used in electric bulbs.


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