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Q1 Give one word for the following:
i. Atoms of same element having different masses.
ii. The central heavy part of the atom containing neutrons and protons.
iii. The number of protons present in the nucleus of an atom.
iv. The outermost electrons of an atom.
v. Elements having 1,2 or 3 electrons in the outermost orbit.
Q2 Fill in the blanks with suitable words.
i. Element with atomic number 16 is‐‐‐‐‐‐‐‐ .
ii. An atom with electronic configuration 2,7 & mass no 19 will have‐‐‐‐ number of neutrons.
iii. The maximum no of electrons in M‐shell is‐‐‐‐‐‐‐ .
iii. The shell closest to the nucleus of an atom is ‐‐‐‐‐‐‐‐‐‐ .
iv. The element having electronic configuration 2,8,3 is ‐‐‐‐‐‐‐‐‐ .
v. The electrons revolve around the nucleus along imaginary path known as ‐‐‐‐‐‐
Q4. 12Mg24&12Mg26 are symbols of two isotopes of magnesium. Compare the atoms of these isotopes
With respect to:
i. The composition of their nuclei.
ii. Their electronic configuration.
iii. Give the reason why the two isotopes of magnesium have different mass numbers.
Q5. Elements X, Y,Z have atomic numbers 6,9 and 12 respectively. Which one:
i. Forms anions;
ii. Forms cations;
iii. Has 4 electrons in the outermost orbit?
Q6. Write down the electronic configuration of the following?
i. 13X27
ii. 17Y35
Write down the number of electrons in X and neutrons in Y and the formula of the compound
Formed by X and Y.
Q7. Three elements P,Q and R have atomic numbers 4,12 and 20 respectively.
i. State the number of valence electrons in each of the elements?
ii. Are these elements metals or non‐metals?
iii. Are these elements going to have similar or different chemical properties?
Q8. Differentiate between the following:
i. Valence shell & penultimate shell.
ii. Nucleus and nucleons.
iii. Octet and Duplet.
iv. Atomic number and mass number.
Q9. Give reasons for the following.
i. Mass number is slightly less than the actual atomic mass.
ii. Helium is chemically extremely unreactive.
iii. The shells surrounding the nucleus of an atom are also called ‘energy levels’ .
Q10. 1)What is the relation between the number of protons and number of electrons in an atom?
2)What would be the reason for an element to have atoms with differing mass numbers.
Answers
1.i ) isotopes
ii) nucleaus
iii) atom will contain a total of 20 protons in its nucleus.
iv)electrons
v)Those elements with 1, 2, or 3 electrons in their outermost shell are the metals
2) i) sulfur
ii)An atom with electronic configuration 2, 7 and mass number 19 will have 10 neutrons
iii)18
iv)K shell
v)orbit
4)i)124 votes
A) the mg(24) contain 12 neutrons and 12 protons but mg(26) contains 14 neutrons and 12 protonsB) ...
5)i)X is carbon
Y is fluorine
Z is magnesium.
Magnesium..... That is...... Z is a cation.
Flourine........ That is.........Y is an anion.
Carbon exhibits the valencies from +4 to -4
6)
KLM
286
(a) Since, it has 6 valence electrons, it belongs to group no. 16.
(b) It has 3 Valence shells, so it belongs to period no 3.
(c) The number of valence electron is 6.
(d) The valency of E is 2 because it requires 2electrons to achieve its stability .
(e) It is a non-metal.
Valency of element X is 2 (2 electrons in the outermost shell) while that of element Y is 1 (1 electron required in the outer most shell to complete octet) So the formula of the compound between X and Y is XY2.
December 27, 2019Toppr
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Solve related Questions
Sodium and chlorine combine to form NaClby electrovalency. Which inert gas configuration does chlorine attain?
1 Verified Answer
Two elements ′X′ and ′Y′ have the following configurations
X=1s22s22p63s23p64s2
Y=1s22s22p63s23p5
The compound formed by the combination of ′X′ and ′Y′ will be x2y3
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Answer:
Explanation:Q1 i isotope ii nucleus ji atomic number iv valence electrons v Na Ca Al
Q2 i sulphur ii 10 neutrons iii 32 electrons iv aluminium v orbit vi