Which of these pairs of elements have the same number of valence electrons?

hydrogen (H) and helium (He)

sodium (Na) and potassium (K)

carbon (C) and oxygen (O)

boron (B) and beryllium (Be)

As the population increases, so does household waste. The most environmentally friendly, and also realistic, solution to this state's household waste problem would be A) more extensive use of landfills. B) building underground waste storage tanks.

Using two different instruments I measured the length of my foot to be 27 centimeters and 27.00 centimeters. Explain the difference between these two measurements.

What is the definition of quanititative observation

When a potassium atom forms an ion, it loses one electron. What is the electrical charge of the potassium ion? A. -2 B. -1 C. +2 D. +1

How many moles is 1.50 x 1023 molecules NH3?

The reaction A (g) ⇌ 2 B (g) A (g) ⇌ 2 B (g) has an equilibrium constant of K = 0.010 K = 0.010. What is the equilibrium constant for the reaction B (g) ⇌ 1 2 A (g) ?

A 0.239 gram sample of a gas in a 100-mL flask exerts a pressure of 603 mm Hg at 14 degrees Celsius. What is the gas?

Which of the following is true about a redox reaction? In a redox reaction, an electron is lost by the reducing agent. In a redox reaction an electron is lost by the oxidizing agent.

Is the equation above balanced? How do you know? Mg + 2HCl → MgCl2 + H2

What characteristics do atoms of carbon-12, carbon-13, and carbon-14 have in common?