An ice tray with 150 g of water at 30C is placed in a freezer at ...

[scienceeasy]

An ice tray with 150 g of water at 30C is placed in a freezer at 5C. How much energy must be removed from the water to lower its temperature to the freezing point?

Question 2

Because we know that the half-lives of many radioactive isotopes are millions of years, we can deduce that
 a. the longer it exists the more radioactive nuclei Earth produces.
  b. the sun is the source of all the radioactive nuclei on Earth.
  c. there must have been many more radioactive nuclei on Earth when life began.
  d. there must have been far fewer radioactive nuclei on Earth before life began.
  e. the natural radioactivity of minerals on the Earth was created by the Earth's internal temperature.

[alvinum]

Answer to Question 1

4.5  103 cal = 4.5 kcal

Answer to Question 2

c

[scienceeasy]

Gracias!

[covalentbond]

Thanks for the timely response, appreciate it