15. Define percent composition.

percent by mass of each element in a compound

18. What are isotones?

Atoms of different elements with the same no. of neutrons

2. An atomic mass unit is defined as

1/12 the mass of a carbon-12 atom

16. what equation shows the relation between mass, molar mass and number of moles?

number of moles= mass /molar mass

the smallest particle of a chemical element that can exist.

20. What are the noble gases?

helium, neon, argon, krypton and xenon

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Chemistry Test

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Questions 20

Answers

1
1. Which of the following is hetero triatomic molecule?
NO2
CO
N3
O3
2
17. Atomicity of phosphorus is
2
4
1
3
3
6. One mole of any gas at STP occupies
27.5 mL
22.4 L
44.8 L
50.0 L
4
10. Atomicity it is the number of atoms present in one molecule of the element
True
False
5
11. GIVE ONE EXAMPLE OF HETEROGENEOUS MIXTURE
SALT AND WATER
MILK
SAND
FOG
6
5. Molecular mass of oxygen gas
16
23
32
8
7
13. which of the following is avagadros number?
6.022 x 1029
6.022 x 1023
5.022 x 1023
6.052 x 1023
8
4. Isotopes differ by the number of
neutrons
protons
electrons
9
15. Define percent composition.
percent of compound in each mole
percent by mole of each element in a compound
percent of electron charge in each compound
percent by mass of each element in a compound
10
18. What are isotones?
Atoms of same element with different no. of neutrons
Atoms of different elements with the same no. of neutrons
Atoms of different elements with same atomic numbers
Atoms of same elements with different atomic numbers
11
8. Atoms of one element cannot be transmuted into atoms of other elements.
True
False
12
19. What stays the same in isotones?
Energy
Nucleons
Neutrons
Protons
13
2. An atomic mass unit is defined as
1/12 the mass of a carbon-12 atom
the mass of 1 carbon atom
12 grams of carbon-12
1/12 the mass of a carbon-12 nucleus
14
9. How many atoms are present in 1.00 mol of sodium?
6.02 x 1023 Na atoms
32.07 Na atoms
22.99 Na atoms
23 Na atoms
15
14. Who discovered the nucleus?
Ernest Rutherford
John Dalton
Eugen Goldstein
James Chadwick
16
3. Who developed the 1st Modern Atomic Theory?
Dalton
Aristotle
Democritus
Bohr
17
16. what equation shows the relation between mass, molar mass and number of moles?
number of moles=mass *molar mass
number of moles= mass /molar mass
mass=molar mass + number of moles
18
12. what is an atom
the biggest particle of a chemical element that can exist.
the roundest particle of a chemical element that can exist.
the smallest particle of a chemical element that can exist.
the flattest particle of a chemical element that can exist
19
20. What are the noble gases?
hydrogen, tin, sliver and calcium
helium, neon, argon, krypton and xenon
potassium, sodium, magnesium and iron
boron, sulfur, arsenic,and iodine
20
7. The sum of the number of protons and the number of neutrons in an atom:
proton number
atomic number
atomic mass
electron number

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