Which element has a smaller atomic radius than strontium (Sr)?

When an object falls through the air and encounters air resistance its overall speed will be than if it had not encountered air resistance? (one word answer)

Which of the following nuclei would be the least stable a 2 protons, 2 neutrons b 1 proton 1 neutron c 1 proton 3 neutrons d 1 proton 2 neutrons

At stp, which substance is the best conductor of electricity? a. nitrogen b. neon c. sulfur d. silver