ለ 12ኛ ክፍል ተፈታኞች መልካም ዜና

ጥያቄዎችን የምታገኙበትን ምርጥ ቻናሎች ልጋብዛቹ ትወዳላቹ።

Natural or Social ናቹ?

ተማርዎች አሁን ምን ያስፈልጋቹሃል?

ለ 12ኛ ክፍል ተፈታኞች መልካም ዜና

ጥያቄዎችን የምታገኙበትን ምርጥ ቻናሎች ልጋብዛቹ ትወዳላቹ።

Chemistry Grade 12 Unit 1
Multiple choice questions with answers

1. What is the pH of a 0.01 M solution of a strong diprotic acid?

a) 1
b) 2
c) Slightly greater than 2
d) Cannot be determined without knowing the acid's identity

2. A solution has a pH of 4. What is its pOH?

a) 4
b) 10
c) 14
d) Cannot be determined without knowing the temperature

3. Which species acts as a Lewis acid in the reaction
BF₃ + NH₃ → F₃B-NH₃?

a) BF₃ b) NH₃
c) F₃B⁻ d) NH₃⁺

4. Which statement best describes an amphiprotic species?

a) It can only accept a proton.
b) It can only donate a proton.
c) It can both donate and accept a proton.
d) It cannot donate or accept a proton

5. A Brønsted-Lowry base is defined as a substance that:

a) Accepts a proton.
b) Donates a proton.
c) Accepts an electron pair.
d) Donates an electron pair.

Answers
1. B
2. B
3. A
4. C
5. A

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የ ስንተኛ ክፍል ተማሪ ናችሁ?

Atomic Spectra

✅Definition:
The atomic spectrum is the range of frequencies of light emitted or absorbed by an atom during electron transitions between energy levels.

✅Types of Spectra:

❄️Emission Spectrum: Produced when electrons drop to lower energy levels and release energy as light.

❄️Absorption Spectrum: Formed when electrons absorb energy and jump to higher energy levels.


✅Key Concepts:

❄️Quantized Energy Levels: Electrons exist in fixed energy levels; they can't exist in between levels.

❄️Photons: Light is emitted or absorbed in packets called photons, with energy proportional to its frequency (E=hv).

❄️Unique to Each Element: Every element has a unique atomic spectrum, like a fingerprint.


❄️Hydrogen Spectrum:

Shows distinct spectral lines grouped into series (e.g., Lyman, Balmer, Paschen).

Example: Balmer series lies in the visible light region.

✅Applications:

❄️Identifying elements in stars (astronomy).

❄️Spectroscopy for chemical analysis.
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Biology Grade 12 Unit 5 Nervous System MCQs with answers.

1. What is the primary function of the nervous system?
A. To produce hormones
B. To transport nutrients
C. To transmit signals between different parts of the body
D. To digest food

Answer: C. To transmit signals between different parts of the body

2. Which part of the nervous system is responsible for voluntary movements?
A. Autonomic nervous system
B. Central nervous system
C. Somatic nervous system
D. Peripheral nervous system

Answer: C. Somatic nervous system

3. What are the basic units of the nervous system?
A. Neurons
B. Glial cells
C. Synapses
D. Axons

Answer: A. Neurons

4. Which part of the neuron receives signals from other neurons?
A. Axon
B. Dendrites
C. Soma
D. Myelin sheath

Answer: B. Dendrites

5. What is the role of myelin in the nervous system?
A. To produce neurotransmitters
B. To protect and insulate axons
C. To receive signals from the environment
D. To connect different types of neurons

Answer: B. To protect and insulate axons

6. Which structure in the brain is responsible for coordinating voluntary movements?
A. Medulla oblongata
B. Cerebellum
C. Hippocampus
D. Hypothalamus

Answer: B. Cerebellum

7. What part of the brain controls the body's involuntary functions, such as
heartbeat and breathing?
A. Cerebrum
B. Medulla oblongata
C. Thalamus
D. Cerebellum

Answer: B. Medulla oblongata

8. Which system controls the fight or flight response?
A. Parasympathetic nervous system
B. Sympathetic nervous system
C. Enteric nervous system
D. Central nervous system

Answer: B. Sympathetic nervous system

9. What is a reflex action?
A. A voluntary response to a stimulus
B. An involuntary response that occurs without conscious thought
C. A slow reaction to pain
D. A learned behavior

Answer: B. An involuntary response that occurs without conscious thought

10. Which part of the nervous system connects the brain to the rest of the body?
A. Central nervous system
B. Peripheral nervous system
C. Reflex arc
D. Sympathetic nervous system

Answer: B. Peripheral nervous system

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