Page 117 - ICSE Chemistry 8

F. Choose the correct op on.
1. The symbol Na of sodium is derived from its La n name _____________.
(a) nallium (b) naƟ um (c) natrium (d) none of these
2. Which of the following elements is represented by the symbol Ag?

(a) Gold (b) Silver (c) Potassium (d) Copper
3. Which of the following elements is tetravalent?
(a) Silicon (b) Lithium (c) Boron (d) Oxygen
4. Which of the following elements exhibits variable valency?

(a) Sodium (b) Hydrogen (c) Aluminium (d) Iodine
5. Which of the following radicals has a valency –2?
(a) Ammonium (b) Sulphate (c) Nitrate (d) Acetate
6. Which of the following is/are limita on(s) of a chemical reac on?

(a) Heat and temperature (b) Pressure
(c) Catalyst (d) All of these

SHORT AND PRECISE

A. Show the given text in the form of fl owcharts.
1. Classifi ca on of elements on the basis of valency
2. Types of ions

3. Types of chemical equa ons

B. Balance the following equa ons.
1. H + O  H O 2. Fe + O  Fe O 3
2
2
2
2
2
3. Mg + O  MgO 4. H + Cl  HCl
2
2
2
5. CH + O  CO + 2H O
2
2
2
4
C. Answer in short.
1. What is a compound? How is it represented?
2. What are valence electrons?
3. How is an anion formed?
4. How is a chemical equa on represented? What does it consist of?
5. What does the atomic theory state?
6. What does the law of conserva on of mass state?

AT LENGTH

A. Diff eren ate between the following.
1. Element and compound
2. Ca on, anion and radical
3. Unbalanced equa on and balanced equa on

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