Question

1. how many elements are present in the compound: na₂s₂o₃

a. 2
b. 3
c. 4
d. 7

1. how many total atoms are present in the compound: mg(oh)₂

a. 3
b. 4
c. 5
d. 7

1. how many total atoms are present in the compound: 2ca(oh)₂

a. 2
b. 3
c. 6
d. 10

Explanation:

Step1: Analyze the first compound \(Na_2S_2O_3\)

In a chemical formula, each capital letter represents a new element. Here, we have \(Na\) (Sodium), \(S\) (Sulfur), and \(O\) (Oxygen). So there are 3 elements.

Step2: Analyze the second compound \(Mg(OH)_2\)

Expand the formula: \(Mg + 2O+ 2H\). Count the atoms: \(1 + 2+ 2=5\)

Step3: Analyze the third compound \(2Ca(OH)_2\)

First, consider one \(Ca(OH)_2\) unit: \(Ca + 2O+ 2H\). Then multiply by 2 (because of the coefficient 2 in front). So \((1 + 2+ 2)\times2 = 10\)

Answer:

1. B. 3
2. C. 5
3. D. 10