You need a 35% alcohol solution. On hand, you have a 280 mL of a 30% alcohol mixture. You also have 75% alcohol mixture. How much of the 75% mixture will you need to add to obtain the desired solution

35 mL

Explanation:

Let the amount of 75% mixture needed be A.

The amount of each solution with their respective concentration to be added together can be expressed as:

0.75A + 0.3(280)eqn 1

The addition of the two solution must merge with the expected concentration and this can be expressed as:

0.35(A + 280)eqn 2

Eqn 1 must be equal to eqn 2, hence:

0.75A + 0.3(280) = 0.35(A + 280)

Solve for A.

0.75A + 84 = 0.35A + 98

0.40A = 14

A = 35

Hence, 35 mL of the 75% mixture will be needed.

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.