Acompound is analyzed and found to contain selenium and bromine. when a specific sample is
examined, it is found to contain 7.928 g of selenium and 32.072 g of bromine. what is the
empirical formula of this compound?
a. se, brg
b. sebra
sebra
d. se, br.

Empirical formula is SeBr₄

Explanation:

Given data:

Mass of selenium = 7.928 g

Mass of bromine = 32.072 g

Empirical formula = ?

Solution:

Number of gram atoms of Se = 7.928/ 78.96 = 0.1

Number of gram atoms of Br = 32.072 / 79.9 = 0.4

Atomic ratio:

            Se                    :               Br          

           0.1/0.1               :               0.4/0.1    

            1                      :                   4        

Se : Br = 1 : 4

Empirical formula is SeBr₄

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.