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Give the answer off all question
1. differentiate between an ions and a free radical
Ans:
Ion
Free Radical
When atom losses or gain electron An atom which has unpaired electron
resulting specie is called ion.
and bears no electrical charge is called
+
For example Cl ,Na
free radical
For example
,
2. What do you know about corpuscular nature of matter?
Ans: According to Empedocles all materials are made of four things called elements
For example earth, water, soil and Fire
3. Differentiate between analytical chemistry and environmental chemistry
Ans:
Analytical Chemistry
Environmental Chemistry
The branch of chemistry that deal with The branch of chemistry that deal with
the methods and instrument for the chemical and toxic substances that
determining the composition of matter pollute the environment and their
is called analytical chemistry.
adverse effect on human being is called
environmental chemistry.
4. What is mole?
Ans: A mole is an amount of substance that contain 6.022x1023 particles of that
substance.
For example: a pair of shoe, a dozen eggs
5. differentiate between an empirical formula and molecular formula
Ans:
Empirical Formula
Molecular Formula
Chemical Formula that gives the Chemical formula that gives actual
simplest whole-number ratio of atoms whole-number ratio of atoms of each
of each element.
element present in a compound.
For example: hydrogen peroxide HO, For example: Hydrogen peroxide H2O2,
1:1
2:2
6. What is the number of molecules in 9.0g of steam?
Molecules=?
Formula
𝑴𝒂𝒔𝒔
Mass= 9.0g
× 𝑵𝑨
Molecules=
𝑴𝒐𝒍𝒂𝒓 𝑴𝒂𝒔𝒔
Molar-mass of H2O= 2(1)+1(16)
= 18g/mole
𝟗
× 6.022x1023
Molecules=
𝟏𝟖
23
NA= 6.022x10
Molecules= 0.5 x 6.022x1023
Molecules= 3.011x1023
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7. What are the molar mass of uranium-238 and uranium-235?
Ans:
U-235
U-238
Molar-Mass=No of atom(Atomic Mass)
Molar-Mass=No of atom(Atomic Mass)
Molar-Mass=1(235)
Molar-Mass=1(238)
Molar-Mass= 235g/mole
Molar-Mass= 238g/mole
8. Why one mole of hydrogen molecules and one mole of H-atoms have different
masses?
Ans:
H-atom
H2-Molecule
Hydrogen atom contain only one Hydrogen molecule contain two atom
hydrogen therefore its mass will be only of hydrogen therefore its mass will be 2
1
For example: 2(1)= 2g
For example: 1(1) = 1g
9. Distinguish between shell and sub shell
Ans:
Shell
Sub-Shell
The electron in an atom revolves around A shell is sub divided in to sub-sub shell.
the nucleus in circular paths called shell. For example: s,p,d and f
For Example: K,L,M and N
10. An atom is electrically neutral why?
Ans: An atom contain same number of proton and electrons therefore electrical
charge is zero and atom act as neutral. For example Na, Cl
11. How many sub-shell are there in N shell?
Ans: There are four sub-shell of N shell and there are s,p,d and f respectively.
12. Give Notation for sub-shell of M shell
Ans: Notation of M-shell are 3s2, 3p6 and 3d10
13. List the sub-shell of M shell in order of increasing energy
Ans: 3s2< 3p6 <3d10
14. Can you identify an atom without knowing number of number of neutrons in it?
Ans: No, if you don't know the number of neutrons then you can't know the atomic
mass of a particular isotope, the atomic mass used for everyday chemistry calculations
is the weighted average of isotopic masses, based on natural occurrence.
15. Write the valance electronic configuration of an element present in a 3rd period and
Group IIIA in periodic table
Ans: 1s2, 2s2, 2p6, 3s2, 3p1
16. write two ways in which isotopes of an element differ
Ans: They have different Atomic Mass and different number of neutron.
17. Which atom has higher shielding effect Li or Na?
Ans: Na atom has higher shielding effect because shielding effect increases down the
group in periodic table and Na places after Li in a same group.
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18. Explain why Na has higher ionization energy than K?
Ans: Na has higher Ionization energy because ionization energy decreases down the
group in periodic table and Na places before K in a same group.
19. Alkali metals belongs to S-block in the periodic table why?
Ans: Because their electronic configuration is completed in s sub-shell therefor alkali
metal belongs to S-Block in periodic table. For example: Li, 1s2, 2s1
20. State octet and duplet rules
Ans:
Octet Rule
Duplet Rule
The tendency of an atom to acquire
The tendency of an atom to acquire
eight electron configuration in their
two electron configuration in their
valence shell, when bonding is called
valence shell, when bonding is called
octet rule.
duplet rule.
For example: Ne. 1s2, 2s2, 2p6
For example: He. 1s2
21. Explain formation of covalent bond between two nitrogen atoms
Ans: Nitrogen is in group V A, so it has five
valence electrons. It needs three electron
to complete its octet. So for sharing each
N-atom contributes three electrons.
For example:
22. How does Al form cation?
Ans: Al belongs to group III A in periodic table
so it has three valence electrons and it has to
loss three electrons to complete its octet in this
way Al forms cation. For example
23. How does O form anion?
Ans: O belongs to group VI A in periodic table, it
has six valence electrons, so it complete its octet it
has to gain two electrons in this way O forms anion.
For example
24. Draw electron cross and dot structure for H2O molecule.
Ans:
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