I will give 20 points plz i need help Which causes genetic variations and can result in different alleles?

predation rate

random mutations

competition

environmental changes

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.

How many lone pairs of electrons are on the central atom of no3- and what is the molecular shape? one, trigonal planar zero, trigonal pyramidal zero, trigonal planar one, tetrahedral one, trigonal pyramidal

Two liquids are poured into a beaker. after a few seconds, the beaker becomes warm. which of the following best describes this reaction? a. an exothermic reaction b. a decomposition reaction c. an endothermic reaction d. a single-displacement reaction