Chemical Reactions
Q: What gas is produced when an acid reacts with a metal?
A: Hydrogen gas.
Q: What does the title of a graph need to include?
A: Both the independent and dependent variables.
Q: What does DNA stand for?
A: Deoxyribonucleic acid.
Q: What does the frequency of a wave tell you?
A: How many waves pass a point per second.
Q: What is the symbol for a resistor?
A: A rectangle.
Q: What is the pH range of acids and alkalis?
A: Acids: 0–6, Alkalis: 8–14.
Q: What is a control variable?
A: Something kept the same to make the test fair.
Q: How many chromosomes are found in a human body cell?
A: 46 chromosomes.
Q: Name two examples of transverse waves.
A: Light waves and water waves.
Q: What happens to current in a parallel circuit?
A: It splits across each branch.
Q: Write a word equation for a reaction between hydrochloric acid and magnesium.
A: Hydrochloric acid + magnesium → magnesium chloride + hydrogen.
Q: How do you calculate the mean from a data set?
A: Add all values and divide by the number of values.
Q: What is a Punnett square used for?
A: Predicting the inheritance of alleles.
Q: What happens to sound waves in a vacuum?
A: They cannot travel; sound needs a medium.
Q: What are the two poles of a magnet called?
A: North and South.
Q: Why is universal indicator better than litmus paper?
A: It shows the strength of the acid/alkali with a full pH range.
Q: Why should a graph start from zero on the y-axis?
A: To avoid misleading scale and ensure accuracy.
Q: What is selective breeding?
A: Choosing parents with desired traits to produce offspring with those traits.
Q: What does a larger amplitude mean in sound?
A: A louder sound.
Q: How can you increase the strength of an electromagnet?
A: Add more coils or increase the current.
Q: Why are Group 1 metals stored in oil?
A: To prevent reactions with air or moisture, as they are highly reactive.
Q: Why do scientists repeat experiments at least three times?
A: To identify anomalies and ensure the results are reliable.
Q: Explain why siblings can look different from each other.
A: They inherit different combinations of genes from their parents.
Q: What is the formula for wave speed?
A: Wave speed = frequency × wavelength.
Q: Why did Mendeleev leave gaps in the periodic table?
A: He predicted the existence and properties of undiscovered elements.