Very Short answers (2*2=4)
4. Write one example for each of the following:
(a) A non- metal with best conductor of heat and a non –metal with poorest conductor of heat.
(b) A metal with dull lustre and a non-metal with lustre
5. (a) Write the conditions necessary for rusting of iron
b) Write the chemical name and Chemical formula of rust.
Short answers (3*4=12)
6. State four reasons for the following facts
(i) Carbon is a non-metal (ii) Copper is a metal
7. (a) Define activity series of metals. Arrange the metals : Gold, Iron, Sodium and calcium in the order of
their decreasing reactivity.
(b) Why metals are electropositive but non-metals are electronegative in nature? Write equations.
Answers
Answer:
Write one example for each of the following:answers
(a) answer:-Silver is best conductor of heat while among metals lead is poorest conductor of heat. Cooper and aluminum are good conductor while mercury is a poor conductor.
(b) answer:-Non-metals vary greatly in appearance. They do not have lustre. As it does not have any free electrons, light falling on non-metals does not reflect and hence non-metals are not shiny.
State four reasons for the following facts answers
(i) answers:-Carbon is the chemical element with the symbol C and atomic number 6 (contains 6 protons in its nucleus). As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds.
(ii) answers:-
- malleable 2. ductile 3. electricity and heat conductors 4. lustrous 5. sonorous 6. high melting and boiling point.
- non malleable 2. non ductile 3. bad conductor 4. non lustrous 5. non sonorous 6. low melting and boiling point.
(7)(b) answers The reactivity series is a series of metals, in order of reactivity from highest to lowest metal. ... According to the activity series, the order of the metals from top to bottom is magnesium, iron, copper and gold. Gold is the least reactive.
(b) Metals are electropositive elements because they can form positive ions by losing electrons. Non-metals are electronegative elements because they can form negative ions by gaining electrons.
Explanation:
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