PLS PLS HELP ME!! Alkali metals (Group 1 elements in the periodic table) are known to be very reactive.
Which statement accurately explains the reactivity of the alkali metals?
A
Alkali metals are very reactive because they all are solids at room temperature.
B
Alkali metals have very low density, which makes them very reactive because they want to gain energy and become stable.
C
Alkali metals are all in Group 1 of the periodic table making them very reactive because the reactivity of a metal increases from right to left across each row.

D
Alkali metals are in Group 1 of the periodic table making them less reactive because the reactivity of a metal increases from left to right across each row.

Astronomers discover an exoplanet (a planet of a star other than the sun) that has an orbital period of 3.87 earth years in its circular orbit around its sun, which is a star with a measured mass of 3.59 x 1030 kg. find the radius of the exoplanet's orbit.

Air is held within a frictionless piston-cylinder container, which is oriented vertically. the mass of the piston is 0.45 kg and the cross-sectional area is 0.0030 m2. initially (state 1) the pressure of the gas is sufficient to support the weight of the piston as well as the force exerted by the atmospheric pressure ( 101.32 kpa). the volume occupied by the air within the cylinder in state 1 is 1.00 liter. one end of a spring (with spring constant k = 1000 n/m) is attached to the top of the piston, while the other end of the spring is attached to a stage that can move vertically. initially the spring is undeflected and therefore exerts no force. then the stage is then moved quasistatically downward a distance of 10.0 cm, at which point the system reaches state 2. the piston-cylinder is not insulated; rather it remains in diathermal contact with the surroundings, which are at a constant temperature of 300 k. what is the change of pressure within the container?

1. a net force of 100 newton’s is applied to a wagon for 5 seconds. this causes the wagon to undergo a change in momentum of