Challenge yourself with these easy questions covering chemistry, biology, physics, and astronomy. Explore key facts about the world around us and discover fundamental science concepts.
How are elements arranged in the periodic table?
Explanation: Elements in the periodic table are arranged by atomic number, which is the number of protons in an atom. Arrangement by weight and chemical reactivity are older approaches or not standard for modern tables. Alphabetical order is not used in scientific classification.
The atomic number of an element is equal to the number of which particle?
Explanation: The atomic number represents the number of protons in an atom's nucleus. Neutrons and electrons can vary in number across isotopes or ions but do not define the atomic number. Ions refer to atoms with a net charge, not a specific type of particle.
Which of the following is NOT an example of a chemical change?
Explanation: Ice melting is a physical change because it only changes the state of water without altering its chemical composition. Food rotting, iron rusting, and paper burning all involve chemical reactions producing new substances.
In an ionic bond, atoms transfer what?
Explanation: Ionic bonds are formed when atoms transfer electrons to achieve stable electron configurations. Protons and neutrons remain in the nucleus and are not transferred in bonding. Energy changes occur but are not 'transferred' in the way electrons are.
What is the pH range of a strong acid?
Explanation: Strong acids have a pH range of 0 to 2, indicating high acidity. 6 to 7 is near neutral, 12 to 14 indicates a strong base, and 4 to 6 is only mildly acidic.
What type of substance can react with acids and neutralize them?
Explanation: Bases react with acids to neutralize them, often producing water and a salt. Enzymes are biological catalysts, catalysts speed up reactions without being consumed, and salts are typically products of acid-base reactions.
What type of reaction absorbs energy from the surroundings?
Explanation: Endothermic reactions absorb energy from their environment. Exothermic reactions release energy, combustion is a specific exothermic reaction, and synthesis refers to making new compounds, not necessarily energy absorption.
When baking soda reacts with vinegar, what gas is produced?
Explanation: The reaction between baking soda and vinegar produces carbon dioxide, which causes bubbling. Oxygen and nitrogen are not produced in this reaction, and hydrogen is involved in different reactions.
Why does salt melt ice?
Explanation: Salt lowers the freezing point of water, which makes it harder for ice to remain solid, causing melting. Salt doesn't increase temperature, doesn't raise the freezing point, and doesn't directly create heat.
What is the basic unit of all living things?
Explanation: Cells are the fundamental unit of structure and function in all living organisms. Atoms and molecules make up all matter, but not specifically living things. Genes carry genetic information within cells.