Suppose the half-life of element k is 20 minutes. if you have a 200 g sample of k, how much of element k will be left after 60 minutes? (do not use significant digits in answering this question).

What must an object gain or lose to become electrically charged? (Choose the best answer) protons electrons neutrons nucleus

What is the formula for an ionic compound made of magnesium and sulfur?

Calculate the volume, in ml. of the 1.0 m naoh stock solution needed to prepare 250 ml of 0.1 molar naoh.

Why is 18-karat gold considered a mixture rather than a pure substance? A) It has a variable composition. B) Its color is different than pure gold. C) The gold atoms are not arranged in a repeating pattern.

A gaseous compound having the empirical formula ch2 has a density of 1.88 g/l at stp. the molecular formula for this compound is (assuming ideal behavior) :

What volume would 3.01•1023 molecules of oxygen gas occupy at STP?

In most food webs there are many producers, fewer herbivores, and even fewer carnivores. Which statement best explains why there are always fewer carnivores than producers in a food web? A. There is not enough space to illustrate them. B.

Which of Deeandra observation is scientifically testable

A round, three dimensional object is a?

The energy needed to start a chemical reaction is called