DSST Physical Sciences 3

Question 1

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

Accepted Answer

340 m/s

Answer

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

Question 2

What is the molar mass of NaCl?

Accepted Answer

58.5 g/mol

Answer

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

Question 3

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

Accepted Answer

Archimedes' Principle

Answer

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

Question 4

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

Accepted Answer

It increases

Answer

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

Question 5

Which quantum number describes the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number (l)

Answer

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

DSST - DANTES Subject Standardized Tests Practice Test