The atoms of some chemical elements have different forms, called isotopes. These break down over time in a process scientists call radioactive decay. Each original isotope, called the parent, gradually decays to form a new isotope, called the daughter. Each isotope is identified with what is called a ‘mass number’. When ‘parent’ uranium-238 decays, for example, it produces subatomic particles, energy and ‘daughter’ lead-206.
91.4 grams
91.4 grams of kcl in grams must be added to 500 ml of a 0. 15 m kcl solution to produce a 0. 40 m solution.
C = mol/volume
2.45M=mol/0.5L
2.45M⋅0.5L = mol
mol = 1.225
Convert no. of moles to grams using the atomic mass of K + Cl
1.225mol * 
mol=1.225
=1.225 mol . 
=1.225 . 74.6
=91.4g
therefore, 91.4 grams of kcl in grams must be added to 500 ml of a 0. 15 m kcl solution to produce a 0. 40 m solution.
What is 1 molar solution?
In order to create a 1 molar (M) solution, 1.0 Gram Molecular Weight of the chemical must be dissolved in 1 liter of water.
58.44 g make up a 1M solution of NaCl.
To learn more about molar solution visit:
brainly.com/question/10053901
#SPJ4
Answer: 17.34 grams of alum will be produced if 0.9875 g of Aluminium foil was used.
Explanation: Reaction to form alum from Aluminium is given as:

We are given Aluminium to be the limiting reactant, so the formation of alum will be dependent on Aluminium because it limits the formation of product.
By stoichiometry,
2 moles of Al is producing 2 moles of Alum
Mass of 2 moles of Aluminium = (2 × 27)g/mol = 54 g/mol
Mass of 2 moles of alum = (2 × 474)g/mol = 948 g/mol
54 g/mol of aluminium will produce 948 g/mol of alum, so

Amount of Alum produced = 17.34 grams
Theoretical yield of alum = 17.34 grams.
C. Mitosis
Mitosis is a process where a single cell divides into two identical daughter cells.
The purpose of which is for growth and to replace worn out cells.
Answer:
5.56 moles H₂O
Explanation:
moles = mass of substance / formula weight of substance
∴moles H₂O = 100 grams / 18 grams/mole = 5.56 moles H₂O