Which element is a metalloid?

a. argon (ar)

b. silicon (si)

c. potassium (k)

d. magnesium (mg) ?

How many atoms of potassium are in 0.250 mol of potassium carbonate, k2co3?

Where the spaces mendeleyev left over any use

Which of the following has the greatest amount of thermal energy? A. 1 L water at 98 °C B. 1 L water at 70 °C C. 250 mL water at 98 °C D. 250 mL water at 70 °C

What could you make by chopping a copper wire into small pieces?

The element europium exists in nature as two isotopes: 151eu has a mass of 150.9196 amu, and 153eu has a mass of 152.9209 amu. the average atomic mass of europium is 151.96 amu. calculate the relative abundance of the two europium isotopes.

The balanced equation below represents the reaction between magnesium metal and hydrochloric acid to produce aqueous magnesium chloride and hydrogen gas. Mg (s) + 2HCl (aq) = = > MgCl2 (aq) + H2 (g) A piece of Mg (s) has a volume of 0.

What is the molarity of a solution prepared by dissolving 33.4 g of sodium chloride in some water and then diluting the solution to a volume of 300.00 mL?

Think about how pressure relates to volume and how gas behavior would change in different volumes. Which of the following will have the largest positive value for Sº? A) 1 mole of helium gas at 1 atm pressure.

Does a reaction stop once it has reached equilibrium? Explain

8 l of water at 19 ∘c are mixed with 1.1 l of water at 47 ∘c in an insulated container. what is the final temperature of the system? express your answer in ∘c