For what value of x do the two ratios suggest a proportional relationship. 13 to 7; x to 98

The correct answer is D.

Explanation:

Let us first write this in a proportional relationship manner:

13 : 7 = x : 98

Now, the easiest way to deal with this kind of problem is to multiply the two outer parts of the proportional relationship on one side and two inner parts on the other side. So:

13 • 98 = x • 7

From here, it's easy to find x:

x = 13 • 98 / 7

x = 182

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6