Question

question 21 of 29
how many atoms of hydrogen? (1.4 points)
extra content
3nahco₃
a. 3
b. 6
c. 9
d. 12
question 22 of 29
how many atoms of chromium? (1.4 points)
extra content
5ga₂(cr₂o₇)₃
a. 10
b. 20
c. 30
d. 40
question 23 of 29
how many atoms of carbon? (1.4 points)
extra content
4k₂co₃
a. 2
b. 4
c. 6
d. 8
e. 10
f. 12

Explanation:

Question 21

Step1: Analyze the formula

In the formula \(3NaHCO_3\), the sub - script of \(H\) (hydrogen) is \(1\), and the coefficient is \(3\).

Step2: Calculate the number of hydrogen atoms

The number of hydrogen atoms \(N = 3\times1=3\)

Question 22

Step1: Analyze the formula

In the formula \(5Ga_2(Cr_2O_7)_3\), the sub - script of \(Cr\) (chromium) inside the parenthesis is \(2\), and the coefficient of the parenthesis is \(3\), and the overall coefficient is \(5\).

Step2: Calculate the number of chromium atoms

First, consider the number of \(Cr\) atoms in one \((Cr_2O_7)\) unit: there are \(2\) \(Cr\) atoms. Then, for \(3\) \((Cr_2O_7)\) units, the number of \(Cr\) atoms is \(2\times3\). Finally, with the coefficient \(5\) for the whole formula, \(N = 5\times2\times3= 30\)

Question 23

Step1: Analyze the formula

In the formula \(4K_2CO_3\), the sub - script of \(C\) (carbon) is \(1\), and the coefficient is \(4\)

Step2: Calculate the number of carbon atoms

The number of carbon atoms \(N=4\times1 = 4\)

Answer:

Question 21: A. 3
Question 22: C. 30
Question 23: B. 4