Grade 🔟
Subject chemistry 🧪
unit 2⃣

1. Which of the following is not a  
   characteristic property of acids?
   A) Sour taste
   B) Ability to turn litmus paper red
   C) Reactivity with metals to 
        produce hydrogen gas
   D) Slippery feel

2. Which of the following is a strong acid?
   A) PH3
   B) CH3COOH
   C) HClO4
   D) HNO2

3. What happens when an acid reacts with a base?
   A) Formation of hydrogen gas
   B) Formation of water and a salt
   C) Increase in pH
   D) Decrease in temperature

4. Which of the following cannot act as an acid?
   A) HCl
   B) NaOH
   C) H2SO4
   D) H2CO3

5. Which of the following represents a weak base?
   A) NaOH
   B) NH3
   C) KOH
   D) Ca(OH)2

6. Which pH value indicates a strong acid?
   A) 2
   B) 7
   C) 10
   D) 14

7. What is the chemical formula for hydrochloric acid?
   A) HNO3
   B) H2SO4
   C) HCl
   D) HClO3

8. Which of the following is a common household base?
   A) Vinegar
   B) Lemon juice
   C) Ammonia
   D) Orange juice
9. What is the concentration of hydrogen ions in a solution with a pH of 3?
    A) 1 x 10^-7 M
    B) 1 x 10^-3 M
    C) 1 x 10^-11 M
    D) 1 x 10^3 M

Answers:
1. D) Slippery feel
2. C) HClO4
3. B) Formation of water and a salt
4. B) NaOH
5. B) NH3
6. A) 2
7. C) HCl
8. C) Ammonia
9. B) 1 x 10^-3 M
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Answer

Q1.
Answer: Option B

Explanation:

Each day of the week is repeated after 7 days.

So, after 63 days, it will be Monday.

After 61 days, it will be Saturday

Q2. Answer: Option A

Explanation:

Let the ages of children be x, (x + 3), (x + 6), (x + 9) and (x + 12) years.

Then, 
》》x + (x + 3)+ (x + 6) + (x+ 9) +(x + 12) = 50

》》 5x = 20

》》x = 4.
Therefore, Age of the youngest child = x = 4 years.

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The endocrine system

👉The endocrine system is made up of organs called glands. The main glands that produce hormones include:
👉Hypothalamus: This gland is located on  brain and controls endocrine system and  determine  other glands, including the pituitary gland, to produce hormones. Also controls  mood, hunger and thirst, sleep patterns and sexual function.
👉Pituitary: is size of a pea and  makes hormones that control several other glands.
👉Thyroid: A gland in the front of  neck that responsible for your metabolism
👉Parathyroid:  control the level of calcium in the body.
👉Adrenal: control metabolism, blood pressure, sexual development and response to stress.
👉Pineal: This gland manages  sleep cycle by releasing melatonin hormone
👉Pancreas:  Makes a hormone called insulin that controls the level of sugar in blood.
👉Ovaries: In women, the ovaries release sex hormones called estrogen, progesterone and testosterone.
👉Testes: In men, make sperm and release the hormone testosterone
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