Question

One mark each
1. Will C-35 and cl - 37 have different valenciesPlustify your answer.
2. Helium atom has 2 electrons in its valence shell but its valency is not justify
3. Define Alloy with two examples.
4. Define atomic mass unit in terms of carbon atom.
5. Case Study
After studying the properties of the subatomic partides of an atom, we can conclude that mass of an
atom is practically due to protons and neutrons alone. These are present in the nucleus of an atom
Hence protons and neutrons are also called nucleons. Therefore, the mass of an atom resides its
nucleus. For example, mass of carbon is 12 u because it has 6 protons and 6 neutrons 6u6w=12
Similarly, the mass of aluminium is 27 u (13 protons 14 neutrons). The mass number is defined as the
sum of the total number of protons and neutrons present in the nucleus of an atom. It is denoted by
A
0. One element can exist as
a) isotopes b) isobars
c) both
d) none
Two elements can exists as
a) isotopes b) isobars
c)both
d) none
No. of neutrons in aluminium atom with atomic no. 13 and mass no. 27 is
a) 13
b)14
c)27
iv) Mass number of an element is same as no. of
a) protons b) neutrons
c) electrons
d) nucleons
2 marks each
6. Surcrose (sugar) crystals obtained from sugarcane and beetroot are mixed together. Will it be a pure
substance or a mixture? Give reasons for the same
7. The atomic number of calcium and argon are 20 and 18 respectively, but the mass number of both
these elements is 40. Define the name given to such a pair of elements. Can you name one more pair of
this type?
3 marks each
8. What are the postulates of Bohr's model of atom and how it has overcome the limitations of
Rutherford's model?
?
9. Is there any difference between valence electron and valency for an element, provide justification with
the help of given elements: Chlorine, Nitrogen and Neon
10. Identify compounds and write their formulae:
(b) Potassium chloride
(c) Iron
(d) Iron sulphide
(e) Aluminium
(1) lodine
(6) Carbon
(h) Carbon monoxide
(i) Sulphur powder
(a) Chlorine gas​

Answer 1

Answer:

it's very big bro

Explanation: