Esteban finds that a small bar of pure gold, with a density of 19.3 g/cm³, displaces 80 cm³ of water. he calculates that it's mass is 1,544 g. he then calculates that a smalller bar, with half the volume of the first bar, has a mass half a great. is he correct? explain your reasoning.

Answer : Yes, he is correct.

Solution : Given,

Density of pure gold =

The pure gold displaces of water that means the Volume of pure gold is equal to the volume of water displaces.

Volume of pure gold =

Now we have to calculate the Mass of pure gold.

Formula used :      

By rearranging the formula, we get the mass of pure gold.

So, The mass of pure gold is 1544 g.

Now we have to calculate the Mass of pure gold when the volume become half.

The density of pure gold remains same because density is an intensive property which means that no matter how much of the substance is present, its value remains same.

Volume of pure gold =      

So, we conclude that when the volume become half then the mass also half.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms