A hypothetical element has an atomic weight of 123.45 g/mol.  It consists of 2 isotopes having masses of 124.05 g/mol and 122.67 g/mol.  What is the percent abundance of the lightest isotope?

During the nuclear decay of the 208Po isotope, two neutrons and two protons are lost, resulting in which isotope?  

How many Cl atoms are in 0.0728 g of PCl3?    

Sodium azide is the chemical used in airbags to inflate them when you crash. It decomposes into elemental sodium and nitrogen gas as shown in the reaction below. Elemental sodium is dangerous because of its high reactivity, so other components, such as KNO3 and SiO2, are added to airbags to react with the sodium and turn it into harmless silicates. Using the balanced reactions below, determine how many moles of K4SiO4 are formed when 4.0 moles of NaN3 reacts. 2 NaN3(s)     →   2 Na(l)    +   3 N2(g) 10 Na(l)   +    2 KNO3(s)   →    K2O(s)  +  5 Na2O(s)  +   N2(g) 2 K2O(s)   +   SiO2(s)  →    K4SiO4(s)

What is the answer to each of the following calculations with proper significant figures? I: 0.0340 x 10500 / 410.0 = ?              II: 34.3 + 97.1 − 2.21= ?         

Write 15,968 in scientific notation.

A 12-oz can of soda pop costs fifty cents. A 2.00 L bottle of the same variety of soda pop costs $1.29. How many times more expensive it is to buy the 12-oz can of pop compared to buying it in a 2.00 L bottle?  (1.00 L = 1.057 quart and 1 quart contains 32 oz) 

The amount of matter occupied by an object.

Write 3.98 x 10-6 in standard form?

Peter Singer’s quality‑of‑life argument may justify euthanasia when life: