We are given with 7.5 moles of oxygen and 7.43 moles of nitrogen.To identify the chemical formula of the compound, we divide each numner by the smaller amount between the two. Hence, oxygen is approx. equal to 1 and nitrogen is equal to 1. Hence teh formula is NO or nitric oxide.

8 0

3 years ago

7. There are 12 singers auditioning for the school musical. In how many ways can the director choose first a lead singer and the

Finger [1]

Answer: The director can choose first a lead singer and then a stand-in for the lead singer in 132 ways.

Step-by-step explanation:

Given : The total number of singers auditioning for the school musical.= 12

The director wanted choose first a lead singer and then a stand-in for the lead singer.

We use Permutations here because order of selecting the singers matters.

The number of permutations of selecting r things out of n things = $^nP_r=\dfrac{n!}{(n-r)!}$

Similarly , the number of ways to select 2 singers in an order from 12 singers

$^{12}P_{2}{=\dfrac{12!}{(12-2)!}$

$=\dfrac{12\times11\times10!}{10!}=132$

Hence, the director can choose first a lead singer and then a stand-in for the lead singer in 132 ways.

8 0

3 years ago