Which of the following is true? Question 12 options:

1. Most organisms present early in Earth's prehistory were more complex than modern organisms.
2. Species on Earth today are but a fraction of all species that ever lived.
3. The number of species existing at one time has decreased throughout history.
4. Extinctions of past species have always happened gradually and on a small scale.
5. Bacteria represent a newer form of life, not present during the early prehistory of Earth.

In the derivation of rrkm theory, a factor of 1/2 is introduced when equalizing the rates of formation and decomposition of activated complex as keal-hr) = ko this is clearly against the assumption of transition state theory that states all the activated complex in the transition state iss going to the product. find the reason why this factor is introduced here.

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

Which two particles are found in the center of an atom