The stage that scientists begin to ask questions and attempt to explain observations is A. forming hypotheses. This is because a hypothesis is basically a testable question about observations scientists make.
A and B can react to form C and D or, in the reverse reaction, C and D can react to form A and B. This is distinct from reversible process in thermodynamics.
Weak acids and bases undertake reversible reactions. For example, carbonic acid: H2CO3 (l) + H2O(l) ⇌ HCO−3 (aq) + H3O+(aq).
The concentrations of reactants and products in an equilibrium mixture are determined by the analytical concentrations of the reagents (A and B or C and D) and the equilibrium constant, K. The magnitude of the equilibrium constant depends on the Gibbs free energy change for the reaction.[2] So, when the free energy change is large (more than about 30 kJ mol−1), then the equilibrium constant is large (log K > 3) and the concentrations of the reactants at equilibrium are very small. Such a reaction is sometimes considered to be an irreversible reaction, although in reality small amounts of the reactants are still expected to be present in the reacting system. A truly irreversible chemical reaction is usually achieved when one of the products exits the reacting system, for example, as does carbon dioxide (volatile) in the reaction
Answer:
C
Explanation:
Flowing water wears away at dirt and rocks
Photosynthesis is the answer
Answer:
B.Gymnoperms produce male cones and female cones, and the pollen from a male cone fertilizes the egg inside a female cone.
