Which of the following elements are nonmetals? a. lithium (li) and barium (ba) b. palladium (pd) and zinc (zn) c. nitrogen (n) and sulfur (s) d. beryllium (be) and magnesium (mg)

C. Nitrogen (N) and sulfur (S)

Explanation:

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In this case, we could differentiate the nonmetals from the metals by understanding they do not have or have very tiny values of properties such as bright, hardness, electric conductivity, heat conductivity and others. Moreover, they are allocated at the right of the periodic table. In such a way, since nitrogen tends to be a gas and sulfur a yellowish powder, they are classified as nonmetals whereas, lithium, barium, palladium, zinc, beryllium and magnesium are considered as metals as they have the aforementioned properties.

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1 × 10⁸ He atoms

Explanation:

Step 1: Given data

Step 2: Convert "d" to meters

We will use the conversion factor 1 m = 10¹² pm.

1 × 10² pm × (1 m / 10¹² pm) = 1 × 10⁻¹⁰ m

Step 3: Convert "D" to meters

We will use the conversion factor 1 m = 100 cm.

1 cm × (1 m / 100 cm) = 0.01 m

Step 4: Calculate the number of atoms of He required

We will use the following expression.

D/d = 0.01 m / 1 × 10⁻¹⁰ m = 1 × 10⁸