Atom

Q.

Chlorine has two isotopes having atomic masses of 35u and 37u each. They are present in the ratio 3:1 respectively. The average atomic mass of Chlorine is _______u.

1. 35

2. 35.5

3. 37

4. 36

Q.

How would you calculate the average atomic mass of copper if 69.2% of copper has a mass of 62.93 amu and 30.8% has a mass of 64.93 amu?

Q. H2COH.CH2OH on heating with periodic acid gives

Q.

The atomic size of an atom increases across the period and decreases down the group.

1. True

2. False

Q.

The metallic character of elements across the period from left to right:

1. Decreases

2. Remains constant

3. Increases

4. First decreases then increase

Q.

If Bromine atom is available in the form of, say, two isotopes ${}_{35}{}^{79}\mathrm{Br}$ (49.7%) and ${}_{35}{}^{81}\mathrm{Br}$ (50.3%), calculate the average atomic mass of Bromine atom.

Q.

Match the type of interaction in column $A$ with the distance dependence of their interaction energy in column $B$:

Column 1	Column 2
Ion-ion	$\frac{1}{r}$
Dipole-dipole	$\frac{1}{r^3}$
London dispersion	$\frac{1}{r^6}$

Q.

According to Dalton's atomic theory, atoms can neither be created nor be destroyed in a chemical reaction.

1. True

2. False

Q.

Metallic character ___ down a group in a periodic table.

Q. Which of the following is not a Döbereiner’s triads?
$[\text{Given: Atomic mass of elements}:Li=6.9,N=14,Na=23,P=31,Cl=35,K=39Ca=40,As=74.9,Br=79.9,Sr=87.6,I=126.9,Ba=137.3]$

1. $Li,Na,K$
2. $Ca,Sr,Ba$
3. $N,P,As$
4. $Cl,Br,I$

Q.

What are some examples of metallic compounds?

Q.

How many unpaired electrons are there in $\mathrm{V}{\left[{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{+3}$?

Q.

Name the most reactive and the least reactive metal.

Q.

The figure represents the reactivity of metals. Which of the following statements are correct?

(i) Sodium is more reactive than magnesium.

(ii) Magnesium and aluminium can displace lead.

(iii) Magnesium and aluminium can displace calcium.

(iv) Iron and tin can displace magnesium.

(v) Most reactive metal is sodium.

(vi) Gold is least reactive.

(vii) Calcium and zinc can displace iron.

1. (i), (ii), (vi), and (vii)
2. (i), (ii), (v), and (vi)
3. (ii), (iii), (vi), and (vii)
4. (ii), (v), (vi), and (vii)

Q. Addition of water to acetylene in presence of suitable catalyst produces

Q.

Metal always found in free state is

1. gold

2. silver

3. copper

4. sodium

Q.

Electrovalent compounds are

1. Polar in Nature

2. Easily available

3. Good conductor of electricity

4. All of the above

Q.

Which valency is Ionisable?

Q.

A hydrocarbon has the following percentage composition:

Hydrogen $=2.2\%$, Carbon $=26.6\%$ and oxygen $=71.2\%$.

Calculate the empirical formula of the compound. If its molecular mass is $90$, find its molecular formula.

$\left[\mathrm{C}=12,\mathrm{H}=1,\mathrm{O}=16\right]$

Q.

Name two metals that are more reactive than Hydrogen?

Q.

Conc. sulphuric acid is a :

1. Drying agent

2. Dehydrating agent

3. Reducing agent

4. Strong acid

Q.

What is the highest valency?

Q. Zinc is more reactive than lead.

1. True
2. False

Q.

An element ‘X’ belongs to 3rd period and group 16 of the Modern Periodic Table.

a) Determine the number of valence electrons and the valency of ‘X’.

b) Molecular formula of the compound when ‘X’ reacts with hydrogen and write its electron dot structure.

c) Name the element ‘X’ and state whether its a metal or a non- metal.

Q.

Identify the most reactive and least reactive metals among the following.

Al, K, Cu, Au

Q.

Name the metal which is placed at the top of the reactivity series.

Q. Elements x, y and z forms Dobereiner's triad. If the atomic mass of element x and z are $7$ and $39$ respectively, then what is the atomic mass of element y?

1. $23$
2. $46$
3. $16$
4. $32$

Q.

The helium atom has $2$ electrons in its valence shell but its valency is not $2$, Explain.

Q.

Name two metals each which are more reactive and less reactive than Hydrogen

Q.

When calcium carbide reacts with water, a colourless gas X with ether-like odour is formed. What is X?

1. CO₂

2. CO

3. C₂H₂

4. CH₄