Tantalum (ta; density = 16.634 g/cm^3 and molar mass = 180.9479 g/mol) has a body-centered cubic structure with a unit-cell edge length of 3.3058 å. use these data to calculate the volume of the tantalum unit cell, the mass of a tantalum unit cell, the number of tantalum atoms in a unit cell, and the number of tantalum atoms in one mole (according to the data presented here).

V = 3.6127x10⁻²³cm³

mass = 6.009x10⁻²²g

2 atoms

6.022x10²³ atoms in 1 mole

Explanation:

The volume of the unit cell is the lenght to the third power.

V = (3.3058x10⁻¹⁰ m )³ = 3.6127x10⁻²⁹m³× (1x10⁶cm / 1m) = 3.6127x10⁻²³cm³

Using density, mass of  a talantalum unit cell is:

3.6127x10⁻²³cm³×(16.634g/cm³)= 6.009x10⁻²²g

As the unit cell is body-centered cube, atoms in an unit cell are:

2 atoms per 6.009x10⁻²²g, 180,9479g (1 mole) contains:

180,9479g × (2atoms / 6.009x10⁻²²g) = 6.022x10²³ atoms in 1 mole

I hope it helps!

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