SCIENCE AND TECHNOLOGY UNIT TEST PAPER

Time: 1 hour  MARKS: 40 MARKS SECTION:'A'                                           

Chapters Covered : SCHOOL OF ELEMENTS , MAGIC OF CHEMICAL REACTION , ELECTRIC SPARK

1. (A) Fill in the blanks. (5 Marks)

1. The horizontal rows in the periodic table are ................ .

2. From left to right, the atomic size of an atom................. .

3. There are ............... periods in the periodic table.

4. An element is placed in group II A, so the number of valence electrons is  ..............

5. An element is placed in 2nd period, so it has ....................... shells.

A.    Answers.

1.     Periods

2.     Decreases

3.     7

4.     2

5.     2

(B) Rewrite the following statements by selecting the correct  options: (5 Marks)

1. Ice changing to water is an example of ....................... change.
2. When copper powder is heated, ....................... is formed.
3. The substances that undergo changes are called as ....................... 

4. Conversion of oil to fats requires ....................... as catalyst.
5. When vegetable oil is mixed with nickel as a catalyst, and heat it with hydrogen gas ....................... are obtained on cooling.

Answers
1.  Physical

2.  Copper oxide

3.  Reactants

4.     Nickel

5.     Fats

2. Attempt the following. (10 Marks)

1. Atomic size decreases across a period.

2. What is the importance of chemical equation?

3. Connecting wires in a circuit are made of copper and aluminium.

4. What do you understand by the term "Redox Reactions"? Explain with one example

 5. The family of noble gases is called as zero group.

3. Attempt the following. (15 Marks)

1. Valency varies gradually across a period.

2.  In modern periodic table, which are the metals, non metals and metalloids among the first 20 elements?

3. Explain the following terms: Rancidity, Endothermic Reactions, Redox reaction

4. Two dissimilar bulbs are connected in series, bulb will be brighter? (Hint: consider the resistance of the bulb).

5. Define the following: 

Reduction reaction.

Corrosion

Double displacement reaction.

Q4. Attempt the following (any 1) ( 5 marks)

1. We feel fresh while on a morning walk in natural surroundings. Why don't we feel the same after 10 a.m. and during rush hours? Write a chemical reaction to support your statement?

2. Explain the Resistors connected in Series.