8th Standard Syllabus & Materials
8th Standard
TN 8th Tamil இயல் 3 - கல்வி கரையில - வினைமுற்று Important Questions And Answers Study Material - QB365 Set A
NEW8th Standard
TN 8th Tamil இயல் 2 - ஈடில்லா இயற்கை - மயங்கொலிகள் Important Questions And Answers Study Material - QB365 Set A
NEW8th Standard
TN 8th Tamil இயல் 2 - ஈடில்லா இயற்கை -பட்டமரம் Important Questions And Answers Study Material - QB365 Set A
NEW8th Standard
TN 8th Tamil இயல் 2 - ஈடில்லா இயற்கை - இயற்கையை போற்றுவோம் Important Questions And Answers Study Material - QB365 Set A
NEW8th Standard
TN 8th Tamil இயல் 1 - தமிழ் இன்பம் - ஆழிக்கு இணை Important Questions And Answers Study Material - QB365 Set A
NEW8th Standard
TN 8th Tamil இயல் 2-ஈடில்லா இயற்கை - திருக்குறள் Important Questions And Answers Study Material - QB365 Set A
Published on: 30/10/2019
Term 2 Atomic Structure
Download Tamil Nadu 8th Standard Science question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.
Questions + Answers key
Take MCQ Science Test1.
In all atoms of an element
the atomic and the mass number are same.
the mass number is same and the atomic number is different
the atomic number is same and the mass number is different
both atomic and mass numbers may vary.
2.
Which of the following statements made by Dalton has not undergone any change?
Atoms cannot be broken.
Atoms combine in small, whole numbers to form compounds.
Elements are made up of atoms.
All atoms of an elements are alike
3.
In water, hydrogen and oxygen are combined in the ratio of _______by mass.
1:8
8:1
2:3
1:3
4.
Cathode rays are made up of
neutral particles
positively charged particles
negatively charged particles
None of the above
5.
The same proportion of carbon and oxygen in the carbon dioxide obtained from different sources proves the law of __________
reciprocal proportion
definite proportion
multiple proportion
conservation of mass
6.
Write the names of the following compounds.
a) CO
b) N2O
c) NO2
d) PCl5
7.
Write the properties of anode rays.
8.
State the law of constant proportions.
9.
State the law of conservation of mass.
10.
How can we prove that the electrons carry negative charge?
11.
Why does a light paddle wheel placed in the path of cathode rays begin to rotate, when cathode rays fall on it?
12.
Balance the following chemical equation.
a) Na + O2 → Na2O
b) Ca + N2 → Ca3N2
c) N2+ H2 →NH3
d) CaCO3 +HCl → CaCl2 + CO2 +H2O
e) Pb(NO3)2 → PbO + NO2 + O2
13.
Write the skeleton equation for the following word equation and then balance them.
a) Carbon + Oxygen → Carbon dioxide
b) Phosphorus + Chlorine → Phosphorus pentachloride.
c) Sulphur + Oxygen → Sulphur dioxide
d) Magnesium + hydrogen → Magnesium + Hydrogen chloride chloride
14.
Write the chemical formula for the following compounds
a) Aluminium sulphate
b) Silver nitrate
c) Magnesium oxide
d) Barium chloride
15.
Find the valency of the element which is underlined in the following formula.
a) NaCl
b) CO2
c) Al (PO4)
d) Ba (NO3)2
e) CaCl2
1.
(c)
the atomic number is same and the mass number is different
2.
(d)
All atoms of an elements are alike
3.
(a)
1:8
4.
(c)
negatively charged particles
5.
(b)
definite proportion
6.
a) CO ➡ Carbon monoxide
b) N2O ➡ Nitrous Oxide
c) NO2 ➡ Nitrogen di oxide
d) PCl5 ➡ Phosphorous Penta Chloride
7.
i) Anode rays travel in straight lines.
ii) Anode rays are made up of material particles.
iii) Anode rays are deflected by electric and magnetic fields.
iv) The properties of anode rays depend upon the nature of the gas taken inside in the discharge tube.
v) The mass of the particle is the same as the atomic mass of the gas taken inside the discharge tube.
8.
Law of constant proportion: In a pure chemical compound the elements are always present in definite proportions by mass.
9.
Law of conservation of mass states that during any chemical change, the total mass of the products is equal to the total mass of the reactants".
10.
J.J. Thomson found that cathode rays were attracted by the positively charged plate and repelled by the negatively charged plate. This led him to the conclusion that the cathode rays (electrons) were made of negatively charged particles.
11.
It is because the small particles of the cathode rays (electrons) have mass and energy. This energy is used in rotating the paddle wheels.
12.
\(a) 4 \mathrm{Na}+\mathrm{O}_{2} \rightarrow 2 \mathrm{Na}_{2} \mathrm{O}\)
\(b) 3 \mathrm{Ca}+\mathrm{N}_{2} \rightarrow \mathrm{Ca}_{3} \mathrm{~N}_{2} \)
\(c) \mathrm{N}_{2}+3 \mathrm{H}_{2} \rightarrow 2 \mathrm{NH}_{3}\)
\(d) \mathrm{CaCO}_{3}+2 \mathrm{HCl} \rightarrow \mathrm{CaCl}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \)
\(e) 2 \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2} \rightarrow 2 \mathrm{PbO}+4 \mathrm{NO}_{2}+\mathrm{O}_{2}\)
13.
\(\text { a) } \mathrm{C}+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}\)
b) skeleton equation : \( \mathrm{P}+\mathrm{Cl}_{2} \rightarrow \mathrm{PCl}_{5} \)
Balanced equation : \( 4 \mathrm{P}+10 \mathrm{Cl}_{2} \rightarrow 4 \mathrm{PCl}_{5} \)
\(\text { c) } \mathrm{S}+\mathrm{O}_{2} \rightarrow \mathrm{SO}_{2}\)
c) skeleton equation : \(\mathrm{Mg}+\mathrm{HCl} \rightarrow \mathrm{MgCl}_{2}+\mathrm{H}_{2} \)
Balanced equation : \(\mathrm{Mg}+2 \mathrm{HCl} \rightarrow \mathrm{MgCl}_{2}+\mathrm{H}_{2} \)
14.
a) Aluminium Sulphate - Al2(SO4)3
b) Silver Nitrate - AgNO3
c) Magnesium Oxide - MgO
d) Barium Chloride - BaCl2
15.
a) NaCl - Na+ - Valency 1
b) CO2 - C - Valency 0
c) Al (PO4) - Al+ - Valency 3
d) Ba (NO3)2 - Ba+ - Valency 2
e) CaCl2 - Ca+ - Valency 2
8th Standard Syllabus & Materials
8th Standard
TN 8th Tamil இயல் 3 - கல்வி கரையில - பாடறிந்து ஒழுகுதல் Important Questions And Answers Study Material - QB365 Set A
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TN 8th Tamil இயல் 3-கல்வி கரையில - பல்துறைக் கல்வி Important Questions And Answers Study Material - QB365 Set A
NEW8th Standard
TN 8th Tamil இயல் 3-கல்வி கரையில - புத்தியைத் தீட்டு Important Questions And Answers Study Material - QB365 Set A
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TN 8th Tamil இயல் 2 - ஈடில்லா இயற்கை - தமிழர் மருத்துவம் ( நேர்காணல்) Important Questions And Answers Study Material - QB365 Set A
Tamilnadu Stateboard 8th Standard Subjects
Tamilnadu Stateboard Standards
