Suppose a laboratory has a 38 g sample of polonium-210. the half-life of polonium-210 is about 138 days.

a. how many half-lives of polonium-210 occur in 1104 days?

b. how much polonium is in the sample 1104 days later?

One mole of liquid water and one mole of solid water have different

Where is the asteroid belt located?

What is the pH of a solution with [H+]=6.2x10-9 M?

The heat of fusion of a substance is the energy measured during a 1. phase change 2. temperature change 3. chemical change 4. pressure change

Which of the following is equal to 0.45 mm3? (B, right?) 4.5 x 10-7 m3 4.5 x 10-10 m3 4.5 x 10-7 cm3 4.5 x 10-3 cm3

What is the pressure, in mm Hg, of 2.50 moles of an ideal gas if it has a volume of 50.0 liters when the temperature is 27.0° C?

What element has the same valence electrons as carbon A) N B) AI C) Si or D) Be

What element is represented by the following electron configuration: 1s22s22p63s23p64s23d4 Question 2 options: Cr Ca Ge Ar

He substance, cocl2, is useful as a humidity indicator because it changes from pale blue to pink as it gains water from moist air. What is its name?

The weighted average atomic mass of an element depends upon the a. relative abundance of protons in the element b. mass and relative abundance of each isotope of that element c. mass and relative abundance of each neutron of that element d.