For the reaction of 2na2o, if you have 18.0 g of na, how many grams of o2 are needed for reaction?

-

6.26 grams

Explanation: -

Atomic Mass of sodium Na = 23 gram

Mass of Na = 18 g

Atomic mass of oxygen O = 16 gram

Molar mass of O2 = 16 x 2 = 32 gram

The balanced chemical equation for the reaction is

4 Na + O2 -- > 2 Na 2 O

From the balanced chemical equation, we see

4 Na requires 1 O2

4 x 23 gram of Na requires 32 gram of O2

18 g of Na gives

= 6.26 grams of O2

For the reaction of formation of Na2O, for 18.0 g of Na, 6.26 grams of O2 are needed for reaction.

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.