Q: Which of the following is the correct formula to calculate the atomic mass of an element with two isotopes, given their masses $m_1$, $m_2$ and abundances $a_1$, $a_2$?

$m_1 \times a_1 + m_2 \times a_2$

Q: Which of the following is the correct formula for calculating the number of neutrons in an atom?

$\text{Mass Number} - \text{Atomic Number}$

Question 1

Which of the following best describes a control variable in a scientific experiment?

Accepted Answer

A variable that is kept constant to ensure that the effect of the independent variable can be measured accurately.

Question 2

Charles Darwin’s theory of natural selection is best supported by which of the following observations?

Accepted Answer

Organisms with traits better suited to their environment tend to survive and reproduce more successfully.

Question 3

Which of the following is the correct formula to calculate the atomic mass of an element with two isotopes, given their masses $m_1$, $m_2$ and abundances $a_1$, $a_2$?

Accepted Answer

$m_1 	imes a_1 + m_2 	imes a_2$

Question 4

A scientist is studying the effect of temperature on enzyme activity. Which is the dependent variable in this experiment?

Accepted Answer

The rate of enzyme activity measured

Question 5

Which of the following best explains why water has a high specific heat?

Accepted Answer

Hydrogen bonds between water molecules require more energy to break.

Question 6

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much will remain after 30 years?

Accepted Answer

10 grams

Question 7

Which of the following molecules is most likely to form hydrogen bonds with water?

Accepted Answer

Ammonia ($NH_3$)

Question 8

Which property of water allows insects like water striders to walk on its surface?

Accepted Answer

High surface tension due to hydrogen bonding

Question 9

Which of the following best describes chemical equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate, so the concentrations of reactants and products remain constant.

Question 10

Which functional group is found in both amino acids and proteins, and is essential for their structure?

Accepted Answer

Carboxyl group ($-COOH$)

Question 11

Which of the following statements about ATP is correct?

Accepted Answer

ATP stores energy in the bonds between its phosphate groups.

Question 12

Which of the following best explains why ice floats on water?

Accepted Answer

Hydrogen bonds in ice create a lattice structure that makes it less dense than liquid water.

Question 13

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$	ext{Mass Number} - 	ext{Atomic Number}$

Question 14

Which of the following best describes a polar molecule?

Accepted Answer

A molecule with an uneven distribution of charge due to differences in electronegativity.

Question 15

Which of the following is a real-world application of radioactive isotopes in medicine?

Accepted Answer

Using isotopes to diagnose and treat diseases such as cancer.

Question 16

Which of the following best explains why water is an excellent solvent?

Accepted Answer

Water’s polarity allows it to surround and separate ions and polar molecules.

Question 17

Which of the following is true about the Miller-Urey experiment?

Accepted Answer

It demonstrated that organic molecules could form spontaneously under early Earth conditions.

Question 18

Which of the following is the correct formula for calculating molarity ($M$) of a solution?

Accepted Answer

$M = \frac{	ext{moles of solute}}{	ext{volume of solution in liters}}$

Question 19

Which of the following best describes the role of functional groups in organic molecules?

Accepted Answer

They determine the physical and chemical properties of the molecule.

Question 20

Which of the following is a correct statement about valence electrons?

Accepted Answer

Valence electrons determine the chemical reactivity of an atom.

General Biology Study Guide: Foundations, Chemistry, Water, and Organic Molecules

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