<span>a) 7.9x10^9 b) 1.5x10^9 c) 3.9x10^4 To determine what percentage of an isotope remains after a given length of time, you can use the formula p = 2^(-x) where p = percentage remaining x = number of half lives expired. The number of half lives expired is simply x = t/h where x = number of half lives expired t = time spent h = length of half life. So the overall formula becomes p = 2^(-t/h) And since we're starting with 1.1x10^10 atoms, we can simply multiply that by the percentage. So, the answers rounding to 2 significant figures are: a) 1.1x10^10 * 2^(-5/10.5) = 1.1x10^10 * 0.718873349 = 7.9x10^9 b) 1.1x10^10 * 2^(-30/10.5) = 1.1x10^10 * 0.138011189 = 1.5x10^9 c) 1.1x10^10 * 2^(-190/10.5) = 1.1x10^10 * 3.57101x10^-6 = 3.9x10^4</span>

4 0

3 years ago

Read 2 more answers

What eventually happens to gas if its pressureis increased?

balu736 [363]

Answer:

the rate increases

Explanation:

they are closer to each other, they will collide with each other more frequently and more successful collision

4 0

2 years ago

"how many grams of calcium are consumed when 156.8 ml of oxygen"

Akimi4 [234]

Your question is incomplete. However, I found a similar problem fromanother website as shown in the attached picture.

To solve this problem, you must know that at STP, the volume for any gas is 22.4 L/mol. So,

Moles O₂: 156.8 mL * 1 L/1000 mL* 1 mol/22.4 L = 0.007 moles
Mass calcium: 0.007 mol O₂ * 2 mol Ca/1 mol O₂ * 40 g/mol Ca =<em> 0.56 g Ca</em>

3 0

2 years ago

What does sodium react with

Pani-rosa [81]

Sodium reacts with water to form a colorless solution of sodium hydroxide and hydrogen gas.

5 0

2 years ago