Atoms and Molecules

Q.

Number of gram atoms of oxygen present in $0.3mole$ of $(COOH{)}_2.2H_{2}O$ is

1. 9

2. 0.9

3. 1.8

4. 18

Q. If we consider that $\frac{1}{6}$, in place of $\frac{1}{12}$, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

1. Decrease twice
2. Increase two fold
3. Remain unchanged

4. Be a function of the molecular mass of the substance

Q. Which of the following statements is incorrect about matter?

1. It occupies space.
2. It doesn't have mass.
3. Can be perceived by senses
4. Atoms are building blocks of matter.

Q. How many hydrogen atoms are present in one molecule of glucose?

1. 6
2. 5
3. 10
4. 12

Q. If an element $X$ exists in its two isotopic form ${}_{17}^{35}X\left(75\%\right)$ and ${}_{17}^{37}X\left(25\%\right)$. The average atomic mass of element $X$ is:

1. $36u$
2. $36.5u$
3. $35.5u$
4. None of these

Q. What is the formula mass unit of ZnO?

1. 81 u
2. 188 u
3. 88 u
4. 18 u

Q.

Question 9(a)
What is the mass of:
(a)0.2 mole of oxygen atoms?

Q. The arrangement of particles of an unknown substance at the same pressure but at two different temperatures is shown in the diagrams.

Which of the following substances could the diagrams represent?

Q.

Which one of the following properties of an element can never be variable?

1. Atomic weight

2. Valency

3. Equivalent Mass

4. All the above

Q. The average atomic mass of a sample of an element X is 16.2u. What are the parcentage of isotopes ${}_8^{16}X$ and ${}_8^{18}X$ in the sample?

Q. Classify the following as molecules of elements or compounds. Water, methane, ozone, phosphorus, nitrogen, slaked lime, salt, vinegar, calcium carbonate.

Q.

Question 1
Which of the following correctly represents 360 g of water?

(i) 2 moles of $H_{2}O$

(ii) 20 moles of water

(iii) $6.022\times {10}^{23}$ molecules of water

(iv) $1.2044\times {10}^{25}$ molecules of water
(a) (i)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)

Q. The ratio of hydrogen to oxygen atoms, in a water molecule is:

1. 1 : 2
2. 2 : 4
3. 1 : 3
4. 2 : 1

Q.

How many oxygen atoms are present in 50g of $CaC{O}_3$?

1. 3.011 $\times$ ${10}^{23}$
2. 6.022 $\times$ ${10}^{23}$
3. 9.033 $\times$ ${10}^{23}$
4. 12.044 $\times$ ${10}^{23}$

Q. Question 7(a)
What is the mass of:
(a) 1 mole of nitrogen atoms?

Q.

Question 7

Why was carbon-12 preferred over oxygen-16 to be chosen as the standard reference for measuring atomic masses?

Q. Question 1
If one mole of carbon atoms weighs 12 grams, what is the mass (in grams) of 1 atom of carbon?

Q.

Choose the correct option regarding polarity of N2 and NH3 ​molecules.

1. $N_2$: polar compound ;
   $N{H}_3$: nonpolar compound
2. $N_2$: nonpolar compound ;
   $N{H}_3$:nonpolar compound
3. $N_2$: nonpolar compound ;
   $N{H}_3$:polar compound
4. $N_2$: polar compound ;
   $N{H}_3$: polar compound

Q. Calculate the number of water molecules present in one drop of water which weighs $0.18g$.

Q. Which has more atoms, 200 grams of sodium or 200 grams of iron?
(given :- Atomic mass of Na = 23 u, Fe = 56 u)

Q. 9.Is atom divisible? If yes then explain

Q.

Explain the following term:

Avogadro constant

Q. Statement 1 (S1): The formula unit mass of a substance is the sum of the masses of all atoms in a formula unit of a compound.

Statement 2 (S2): The formula unit mass of ${\text{MgCl}}_2$ is 95 u.

1. Only S1 is true
2. Both S1 and S2 are false
3. Both S1 and S2 are true
4. Only S2 is true

Q. Is there any other type of matter except solid, liquid and gas?

Q. Assertion :The ratio weights of carbon and oxygen in $C{O}_2$ is $3:8$ and it is a constant. Reason: The atomic weights of carbon and oxygen are a constant.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
3. Assertion is correct but Reason is incorrect.
4. Assertion is incorrect but Reason is correct.

Q. Which of the following contains the largest number of oxygen atoms?

1. 1 g of $O$
2. 1 g of $O_2$
3. 1 g of $O_3$
4. All have same number of atoms

Q. Matter is made of atoms.

1. True
2. False

Q. What is the statement of Democritus about atoms?

Q. The number of atoms present in 0.5 mole of nitrogen is same as the atoms in:
(a)12 g of C (b) 64 g of S
(c) 8 g of O (d) 48 g of mg

Q.

If one mole of carbon atoms weighs 12 grams, what is the mass (in grams) of 1 atom of carbon?