49.Which of the following statements regarding chemical equilibrium is true?

You have 400 kg of a radioactive substance with a short half-life of 1000 years. how much will be left after these times?

Amiraneli [1.4K]

Half-life of a radioactive substance is the time required to reduce the amount of substance to half of its initial amount.

In present case, half-life is material is given as 1000 years and initial amount of material is given as 400 kg

Answer 1) Since, half-life of radio-active substance is 1000 years, therefore after 1st half life, amount of the material will be left to half the initial amount. Hence, amount of substance left after 1000 years = 400/2 = 200 kg.

Answer 2) For 2000 years, radioactive material has crossed 2 times the half life. Therefore , amount of the material will be left to 1/4 the initial amount. Hence, amount of substance left after 2000 years = 400/4 = 100 kg.

Answer 3) For 4000 years, radioactive material has crossed 4 times the half life. Therefore , amount of the material will be left to 1/16 the initial amount. Hence, amount of substance left after 4000 years = 400/16 = 25 kg.

8 0

4 years ago

2. Which substance has the greatest molecular

storchak [24]

Answer:

Choice 4 easy

Explanation:

4 0

3 years ago

Please help me I will give a brainleist

Korvikt [17]

When the dew point temperature and air temperature are equal, the air is said to be saturated. Dew point temperature is NEVER GREATER than the air temperature. Therefore, if the air cools, moisture must be removed from the air and this is accomplished through condensation.

7 0

3 years ago

Planet A is an inner planet with no moon and hardly any atmosphere. Planet B is an inner planet with no moon but with a dense at

postnew [5]

I think the answers are Mars and Venus

7 0

3 years ago

A cylinder contains 250 g of Helium at 200 K. The external pressure is constant at 1 atm. The temperature of the system is raise

Black_prince [1.1K]

Answer:

There is 96200 J or 96 kJ of heat released.

Explanation:

Step 1: Data given

Mass of helium = 250 grams

Temperature = 200 K

Temperature is raised by 74 K

The heat capacity of helium = 20.8 J/mol*K

Molecular weight for helium = 4 g/mol

Step 2: Calculate moles of Helium

Moles of Helium = mass of Helium / molar mass of helium

Moles of helium = 250 grams / 4g/mol

Moles of helium = 62.5 moles

Step 3: Calculate heat

Q = n*c*ΔT or

⇒ with Q = the heat released in Joule

⇒ with n = moles of helium = 62.5 moles

⇒ with c = the heat capacity of helium = 20.8 J/mol*K

⇒ with ΔT = the change in temperature = T2 - T1 = 74 K

Q = 62.5 mol * 20.8 J/mol*K * 74 K

Q = 96200 J = 96 kJ

Since the temperature is raised, this is an exothermic reaction. The heat is released.

There is 96200 J or 96 kJ of heat released.

8 0

3 years ago