Which of the following is an example of how a scientist might use a model a. a stopwatch is used to time the rate of a chemical reaction. b. a microscope is used to magnify a group of cells on a slide. c. a wrench is used to tighten a nut on a piece of wood. d. the end of a slinky is moved vertically up and down to simulate a wave.

The correct answer will be option-D.

Explanation:

A scientific model is the simplified visual representation of the complex system which occurs in nature.

The scientific models used could be 2 dimensional or 3-dimensional representation of the phenomenon which plays an important role in the scientific world. The are used by the scientist to explain the phenomenon to the layman as well as by the researchers to prove the hypothesis.

In the given option, the best example of the scientific model will be the one which uses the up-down movement of the slinky which represents the movement of the waves as the travelling waves are invisible to humans.

Thus, option-D is the correct answer.

b..

is the correct one

explanation:

covalent bonds form as valence electrons are shared between two atoms. lewis structures and structural formulas are common ways of showing the covalent bonding in organic molecules. formal charge describes the changes in the number of valence electrons as an atom becomes bonded into a molecule.

answer: e.   sour taste

explanation: acids are those substances which dissociates in water to give ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. acids are sour in taste. example: hcl

bases are those substances which dissociates in water to give ions or accepts ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. bases are bitter in taste. bases are slippery in nature.