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Chemistry
1. Assume you are listening bisrat FM 101.1 MHz live football streaming by host of Mesele Mengistu. Find the wave length of these radio wave ?
A. 3m
B.300nm
C. 1.5m
D. 1500 nm
Answer : A
C=ለ×f
ለ=C/f =3×10^8/101.1×10^6
=0.0296 ×10²=3m


2. Which electron excitation have the lowest quantum of energy?
A.ni=1 and nf=2
B. ni=2 and nf=3
C. ni=3 and nf=4
D. ni=5 and nf=6

Answer :D
as quantum number increases ,quantum energy decreases!
3. There is a minimum frequency needed to emits silver electrons with specfic light of wave length 400nm.and atinstant it emit its electron by blue light of wave length 700nm .What is its kenetic energy ?
A.1.65 ×1^-17j
B. 8.24×10^18 j
C. 1.2×10^-19 j
D. 5× 10^-20 j

Answer : no answer
KE=h(v -v°)
KE= hc(1/ለ -1/ለ°)
=2.13×10-19 sorry for calculation error

4.One of the following have a high electro magnetic radiation , which one?
A. Alpha particles
B. Betta particles
C. Gamma rays
D. X rays
Answer:C
Gamma > X ray
Note that particles don't have EMR nature
5. Calculate the wave length of a silver electron that is emitted by certain light wave ?
A. 1.2×10-¹¹m
B. 2.4 ×10-¹²m
C. 6×10-¹³ m
D. 645nm
Answer:B
Mc²=hc/ለ
ለ=h/MeC
=6.26×10^-34/9.11×10-³¹(3×10^8
= 0.24×10-¹¹
6. Which one the following is true about position and location of electron ?
A. We can find the position and direction of electron at instant time around the orbit?
B. The position of Valance electrons are determineable while the inner is impossible.
C. The position of electron fixed at its orbital state
D. The spontaneous determination of electrons' position is impossible.

Answer:D
Remember Heisenberg uncertainty principle .


7.Which of the following was discovered by using alpha scattering experiment ?
A.Electron
B.Neutron
C.Proton
D. Nucleus

Answer:D
Nucleus was discovered by E.Rutherford using alpha scattering experiment
8.Which one of the following electron configuration principle is correctly matched with its ideology?
A. Aufbau principle States that each of 2p orbitals will hold a single electron before any of them receive the second electron.
B. Pauli exclusion principle- no two electrons can have the same quantum number ?
C. Hindus principle- electrons occupy the lowest energy orbital.
D. Pauli's exclusion principle:electrons occupy the lowest energy orbital before entering the higher energy orbital

Answer:B
Aufbau principle -electron occupy the lowest energy orbital
Hund's principle -equal energy orbitals are each occupied by a single electron before the second electron of opposite spin enters the orbital
Pauli exclusion Principe -no two electrons can have the same 4 quantum number.

9. One of the following decrease as we go down the group?
A.Electron affinity
B.Atomic size
C.Metallic character
D. Atomic radius
Answer:A
Electron affinity decrease down agroup
10.Which one is not radioactive element?
A.Ra
B.C
C.Ag
D.N
Answer:C
Radioactivity is the spontaneous emission of radiation from unstable nuclei of certain isotopes
Example of radioactive element are Cr,Ra,C,N,U

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Answers to the above chemistry quistions

Chemistry -unit -2
1. Assume you are listening bisrat FM 101.1 MHz live football streaming by host of Mesele Mengistu. Find the wave length of these radio wave ?
A. 3m
B.300nm
C. 1.5m
D. 1500 nm

2. Which electron excitation have the lowest quantum of energy?
A.ni=1 and nf=2
B. ni=2 and nf=3
C. ni=3 and nf=4
D. ni=5 and nf=6

3. There is a minimum frequency needed to emits silver electrons with specfic light of wave length 400nm.and atinstant it emit its electron by blue light of wave length 700nm .What is its kenetic energy ?
A.1.65 ×1^-17j
B. 8.24×10^18 j
C. 1.2×10^-19 j
D. 5× 10^-20 j

4.One of the following have a high electro magnetic radiation , which one?
A. Alpha particles
B. Betta particles
C. Gamma rays
D. X rays

5. Calculate the wave length of a silver electron that is emitted by certain light wave ?
A. 1.2×10-¹¹m
B. 2.4 ×10-¹²m
C. 6×10-¹³ m
D. 645nm

6. Which one the following is true about position and location of electron ?
A. We can find the position and direction of electron at instant time around the orbit?
B. The position of Valance electrons are determineable while the inner is impossible.
C. The position of electron fixed at its orbital state
D. The spontaneous determination of electrons' position is impossible.

7.Which of the following was discovered by using alpha scattering experiment ?
A.Electron
B.Neutron
C.Proton
D. Nucleus

8.Which one of the following electron configuration principle is correctly matched with its ideology?
A. Aufbau principle States that each of 2p orbitals will hold a single electron before any of them receive the second electron.
B. Pauli exclusion principle- no two electrons can have the same quantum number ?
C. Hindus principle- electrons occupy the lowest energy orbital.
D. Pauli's exclusion principle:electrons occupy the lowest energy orbital before entering the higher energy orbital

9. One of the following decrease as we go down the group?
A.Electron affinity
B.Atomic size
C.Metallic character
D. Atomic radius

10.Which one is not radioactive element?
A.Ra
B.C
C.Ag
D.N



@high_preparatory

Quiz for grade 12 👇👇👇👇👇

1.Which word is the odd man out?
A. hate
B. fondness
C. liking
D. attachment
2. Look at this series: 36, 34, 30, 28, 24, … What number should come next?
A. 22
B. 26
C. 23
D. 20
3.Which word does NOT belong with the others?
A. index
B. glossary
C. chapter
D. book
4 Which word does NOT belong with the others?
A. wing
B. fin
C. beak
D. rudder
5. Safe : Secure :: Protect :
A. Lock
B. Guard
C. Sure
D. Con
6.Which word is the odd man out?
A. trivial
B. unimportant
C. important
D. insignificant
7.Pick the odd man out?
A. just
B. fair
C. equitable
D. biased
8.Melt : Liquid :: Freeze :
A. Ice
B. Solid
C. Condense
D. Push