Question

When element X bonds to hydroxide (OH-), it forms X(OH)2.

The molar mass of element X is 40.08 g/mol. What is the molar mass of the compound?

A.74.1 g/mol

B.29.06 g/mol

C.57.06 g/mol

D.34.1 g/mol

Answer 1

Explanation:

75 g/mol

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Answer 2

Answer:

Let x and y be the atomic weights of X and Y

Given 0.1 mole of XY  

2

​  

 weighs 10g

⇒x+2y=  

0.1

10

​  

=100⟶(1)

0.05 mole of X  

3

​  

Y  

2

​  

 weighs 9g

⇒3x+2y=  

0.05

9

​  

=180⟶(2)

(1)⇒x=100−2y

Substituting for x in Equation (2)

⇒3(100−2y)+2y=180

⇒300−6y+2y=180

⇒y=30

Hence x=100−2(30)=40

Explanation: