7. You have 1.5x1024 atoms of iron. How many moles do you have?

2.49moles

Explanation:

To calculate the number of moles (n), of iron (Fe) in 1.5 × 10²⁴ atoms, we divide the number of atoms by Avogadro's number (6.02 × 10²³).

That is, n = N ÷ nA

Where;

n = number of moles (mol)

N = number of atoms

nA = Avogadro's constant

n = 1.5 × 10²⁴ ÷ 6.02 × 10²³

n = 1.5/6.02 × 10(²⁴ - ²³)

n = 0.249 × 10¹

n = 2.49moles

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.