A piece of copper is 2x2x4 cm and has a mass of 142, what is the density of copper

Consider the reaction of hydrogen gas with chlorine gas: H2 + Cl2 → 2HCl 4 molecules of hydrogen gas react with 6 molecules of chlorine gas. 4 molecules of hydrogen gas in this reaction will produce 8 molecules of HCl.

What advances in science have been made as a result of radiometric dating?

Which instrument is directly used to determine the relative masses of atoms? (A) spectroscope (B) Geiger counter (C) mass spectrograph (D) microbalance (E) electron microscope

Indicate the number corresponding to each coefficient required to write the balanced equation for the reaction: aH2SO4 + bKOH cH2O + dK2SO4

All of the following are true statements about heterogenous mixtures except for one. Which statement is false? A. An example of a heterogeneous mixture is muddy water. B. The particles of a heterogeneous mixture will not interact. C.

How many molecules of sulfur trioxide are in 78.0 grams? (A) 7.33 x 10^23 (B) 5.87 x 10^23 (C) 3.76 x 10^27 (D) 0.974 (E) none of the above

How many different elements have scientists discovered? 12, 112, 118, or more than 500?

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

Which of the following household appliances is designed to directly convert electrical energy to heat energy? A. a can opener B. a stove C. a garbage disposal D. a fan

What volume will 12.0 g of oxygen gas occupy at 25 c and a pressure of 52.7 kpa?