Which of the following statements about semi-empirical methods are true:
It combines a theoretically sound model of bonding with some experimentally determined parameters.
It gives an exact solution to quantum mechanical equations.
It treats bonds simply as springs.
It is faster to calculate than ab initio methods.

It combines a theoretically sound model of bonding with some experimentally determined parameters

It is faster to calculate than ab initio methods.

step-by-step explanation: Semi-emperical methods are fast and accurate in giving computational result for large molecules. Semi-emperical methods combines theoretically sound models of bonding with some experimentally determined parameters. It is based on Hartree-fock calculation,it is about the simplest form of Hartree-fock calculation It is also faster to calculate than ab initio methods.

the expression (1.26)2t reveals the approximate rate of increases in the number of plants semiannually.

hope this : )

square root of 36/6 = 2.449489743

square root of 16/6 = 1.632993162

square root of 6 = 2.449489743

the answer is square root of 16/6 because the square root of 36/6 is the same answer as square root of 6 = 2.449489743