Which two elements have the same number of valence electrons?

Na and Sr

Zr and H

O and S

Mg and P

Is PbO2 ionic or covalent

What are three main classifications of the elements

Taking a cross section of a fiber can reveal what?

In a hydrochloric acid solution, where the [HCl] is 0.010 M, what is the pH? pH = 2.0 pH = 12.0 pH = 3.0 pH = 11.0

What type of radiation is lead emitting in the following equation? alpha particles beta particles gamma rays

If the heat released during condensation goes only to warming the iron block, what is the final temperature (in ∘C∘C) of the iron block? (Assume a constant enthalpy of vaporization for water of 44.0 kJ/molkJ/mol.)

Which of the following is not a disaccharide? A) sucrose B) maltose C) lactose D) amylose E) all of the above are disaccarides

The process by which a semipermeable membrane allows water molecules, small molecules, and ions to pass through while retaining large particles

Ice melting, water boiling, lighting a match, grape juice freezing. Which statement describes evidence of a chemical reaction

An ion from a given element has 22 protons and 18 electrons. what is the charge on the ion?