When 1.375 g of copper (ii) oxide is reduced on heating in a current of hydrogen, the weight of copper remaining after the reaction is complete is 1.098 g. what is the percent composition of oxygen?

20.11% of oxygen

Explanation:

The reaction is:

2CuO ⇒ 2Cu + O2

If you have an initial amoung of a sample, thi may be have impurities, so you have to start from products to know what you had at the begining.

to make a relation between reagents and products you need to change the mass to mol, then you can relate them with the molar ratio.

Now you have the initial amount of oxygen, to convert to percent you must divide the mass of oxygen between the mass of the sample and multiply by 100

explanation:

venn diagram is pictorial representation with of circles showing the relation between two finite sets or things. the intersection part of two circles conveys the relation present in between those sets or things.

here in the venn diagram of sand and salt two circles represent sand and salt. but the area falling under the intersection of these circle represents the mixture of sand and salt.

so, in a venn diagram the mixture will be placed in a middle that is in between the intersection of two circles.