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)

How would the kinetic energy of a 12,000 kg train compare with the kinetic energy of a 900 kg compact car if both were traveling at the same speed? A. the trains kinetic energy would be equal to the cars kinetic energy. B.

What happens to the speed of an object when dropped at free fall?

A fictitious element X is composed of 10.0 percent of the isotope 55X, 20.0 percent of the isotope 56X, and 70.0 percent of the isotope 57X. Calculate the weighted atomic mass of element X to the nearest tenth.

Describe how a cold front affects weather.

Which 0f the following describes the electron sharing between hydrogine and flourine

How does a mixture of benzoic acid and benzaldehyde can be isolated separately by extractions?

What is a compound? a) a combination of two or more substances that are not chemically combined b) a combination of two or more elements that are combined in a certain ratio

A gas has a volume of 75mL at a pressure of 200.0 kPa. What will be the new volume be in mL if the pressure is decreased to 60.0 kPa in sig figs

Give two reasons why it's important to work with a partner in a lab

Suppose you have 3.00*1018 reams of lead (pb). how many lead atoms do you have? express the number of atoms numerically.