Physical Sciences Flashcards

A wave has a frequency of 500 Hz and a wavelength of 0.68 m. What is its speed?

Answer: 340 m/s

Wave speed = frequency × wavelength = 500 Hz × 0.68 m = 340 m/s (speed of sound in air).

What is the molar mass of NaCl?

Answer: 58.5 g/mol

Molar mass of NaCl = Na (23 g/mol) + Cl (35.5 g/mol) = 58.5 g/mol.

Which principle states that the buoyant force on an object equals the weight of the fluid displaced?

Answer: Archimedes' Principle

Archimedes' Principle describes why objects float or sink based on displaced fluid weight.

In a chemical reaction, if the activation energy is lowered by a catalyst, what happens to the reaction rate?

Answer: It increases

Lowering activation energy allows more molecules to have sufficient energy to react, increasing the reaction rate.

Which quantum number describes the shape of an atomic orbital?

Answer: Angular momentum quantum number (l)

The angular momentum quantum number (l) defines orbital shapes: 0=s, 1=p, 2=d, 3=f.

What happens to electrical resistance when the temperature of a conductor increases?

Answer: Resistance increases

In metallic conductors, increased temperature causes more atomic vibrations, impeding electron flow and raising resistance.

Which of the following is an example of a physical change?

Answer: Dissolving salt in water

Dissolving salt in water is physical because the NaCl can be recovered by evaporation — no new substance is formed.