Complete the following crossword puzzle (Fig. 3.1) by using the name of the chemical elements. Use the data given in Table 3.2. Table 3.2 Across Down 2 . The element used by Rutherford during his a-scattering experiment. 1 . A white lustrous metal used for making ornaments and which tends to get tarnished black in the presence of moist air. 3 . An element which forms rust on exposure to moist air. 4 . Both brass and bronze are alloys of the element. 5 . A very reactive non-metal stored underwater. 6 . The metal which exists in the liquid state at room temperature 7 . Zinc metal when treated with dilute hydrochloric acid produces a gas of this element which when tested with burning splinter produces a pop sound. 8 . An element with symbol Pb. (Fig. 3.1)

1.Silver is used to making ornaments. 2.Rutherford used Gold. 3. Iron get rusted in moisture. 4. Brass and bronze are alloys of Copper. It is highly malleable and ductile. 5. Phosphorus is very reactive non-metal. 6. Mercury exists as liquid at room temperature. 7. Hydrogen gas burns with a pop sound when brought close to a burning splinter. It is the lightest elements in the periodic table. 8. Lead is the chemical element with atomic number 82 and has a symbol of Pb from the Latin word Plumbum.

HARD

9th CBSE

IMPORTANT

Earn 100

A silver ornament of mass $' m'$ gram is polished with gold equivalent to $1 %$ of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

Important Questions on Atoms and Molecules

HARD

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 43

A sample of ethane

(C_{2} H_{6})

gas has the same mass as

1.5 x 10^{20}

molecules of methane

({CH}_{4})

. How many

C_{2} H_{6}

does the sample of gas contain?

EASY

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 44

In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called the law of conservation of _____.

EASY

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 44

A group of atoms carrying a fixed charge on them is called _____ ion. (diatomic/ polyatomic)

EASY

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 44

The formula unit mass of

{Ca}_{3} ({PO}_{4})_{2}

is _____.

HARD

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 45

Complete the following crossword puzzle (Fig. 3.1) by using the name of the chemical elements. Use the data given in Table 3.2.

Table 3.2

	Across		Down
$2 .$	The element used by Rutherford during his a-scattering experiment.	$1 .$	A white lustrous metal used for making ornaments and which tends to get tarnished black in the presence of moist air.
$3 .$	An element which forms rust on exposure to moist air.	$4 .$	Both brass and bronze are alloys of the element.
$5 .$	A very reactive non-metal stored underwater.	$6 .$	The metal which exists in the liquid state at room temperature
$7 .$	Zinc metal when treated with dilute hydrochloric acid produces a gas of this element which when tested with burning splinter produces a pop sound.	$8 .$	An element with symbol Pb.

Question Image

(Fig. 3.1)

MEDIUM

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 46

(a) In this crossword puzzle, names of $11$ elements are hidden. Symbols of these are given below. Complete the puzzle.

1. $Cl$ 7. $He$

2. $H$ 8. $F$

3. $Ar$ 9. $Kr$

4. $O$ 10. $Rn$

5. $Xe$ 11. $Ne$

6. $N$

Question Image

(b) Identify the total number of inert gases, their names and symbol from this crossword puzzle.

EASY

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 47

Write the formula for the following and calculate the molecular mass.

Caustic potash

MEDIUM

9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 3 - Atoms and Molecules>Long Answer Questions>Q 47

Write the formula for the following and calculate the molecular.

Baking powder

A silver ornament of mass 'm' gram is polished with gold equivalent to 1 % of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

Important Questions on Atoms and Molecules

Learn and Prepare for any exam you want !

A silver ornament of mass $' m'$ gram is polished with gold equivalent to $1 %$ of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.