What is the total mass of Kr-42 remaining in a 20-mg sample after 48.8 hours?

(1) 2.5 mg

(2) 5.0 mg

(3) 10 mg

4) 20 mg

What is the mass of 1.867 moles of the element chlorine

A 50 L container holds 100 grams of nitrogen gas at a pressure of 45,000 pascals. Calculate the temperature of the nitrogen gas.

Are elements with similar chemical properties found in the same period or group on the periodic table?

Consider again the solution made by diluting 10.0 mL of the 0.50 M NaCl by adding distilled water until 100 mL of solution are produced. Has the concentration of the diluted salt solution increased, decreased, or remained constant?

H2SO4 reacts with NaOH, producing water and sodium sulfate. What volume of 2.0 M H2SO4 will be required to react completely with 75 mL of 0.50 mol/L NaOH? show your work

The volume of 1 mole of o2 gas at T=273k P=1atm is? A 6.02 x 10^-23 ml B 760 L C 22.4 L D 2.24 L E 224 L

There are two stable isotopes of bromine. Their masses are 78.9183 and 80.9163 amu. If the average atomic mass of bromine is 79.9091 amu, what is the natural abundance of the heavier isotope? percent abundance of 81Br __%

If 1.00 mol of argon is placed in a 0.500-L container at 20.0 ∘C, what is the difference between the ideal pressure (as predicted by the ideal gas law) and the real pressure (as predicted by the van der Waals equation) ? For argon, a=1.

Which of these is a covalent compound? 1. AICI3 2. CO 3. MgO 4. LiCI

What is a protein used for