Is Helium a compound, element, or. mixture

Suppose you are performing a gas-producing reaction with an unknown metal, X. X (s) + 2 H C l (a q) ⟶ X C l 2 (a q) + H 2 (g) A sample of 0.243 g of the unknown metal produces 76.9 mL of H 2 gas.

Methane, or CH4, is an example of a molecule whose atoms are held together by which of the following? A. hydrogen bonds B. covalent bonds C. metallic bonds D. ionic bonds

Deffin dilute concentrated or a saturated solution

What is the balanced equation for Sodium reacts with water to form sodium hydroxide and hydrogen gas?

An covered pot of soup is simmering on a stove, and there are water droplets on the wall above the back of the stove. What sequence can you infer has occurred?

Is sidewalk cement an element or a compound?

1.4 Explain why it is important to support individuals to challenge information about services that may present a barrier to participation

Which describes energy changes during nuclear fission? A very large amount of energy is produced from a tremendous mass. EEUU A very large amount of energy is produced from a very small mass. G .

A 0.75mol calcium carbonate (CaCO3) pellet has what mass?

The pH of the acid in the stomach is 2. When a person has heartburn, the acid in their stomach is coming up the esophagus (lower throat) and burning the lining of the esophagus. Why would a person take an Alka Seltzer tablet for heartburn?