Chemistry Regent - Aug 2015 Q11-20

1 Given the balanced equation:
F₂ + energy → F + F
Which statement describes what occurs during this reaction? 

• Energy is absorbed as a bond is formed. 
• Energy is absorbed as a bond is broken. 
• Energy is released as a bond is formed.
• Energy is released as a bond is broken. 

Which atoms will bond when valence electrons are transferred from one atom to the other? 

• O and Se
• O and Sr
• O and H
• O and P

 Which sample of matter is a mixture? 

• Br2(ℓ) 
• K(s)
• KBr(s)
• KBr(aq)

According to kinetic molecular theory, collisions between gas particles in a sample of an ideal gas

• increase the energy content of the gas sample 
• produce strong attractive forces between the gas particles 
• result in a net loss of energy by the gas sample 
• transfer energy between the gas particles

Which substance can not be broken down by a chemical change? 

• ethane
• propanone
• silicon
• water

 The temperature of a sample of matter is a measure of the 

• average potential energy of the particles of the sample
• average kinetic energy of the particles of the sample 
• total nuclear energy of the sample
• total thermal energy of the sample

7 Under which conditions of temperature and pressure does a real gas behave most like an ideal gas? 

• 37 K and 1 atm
• 37 K and 8 atm
• 347 K and 1 atm
• 347 K and 8 atm

 The ratio of chromium to iron to carbon varies among the different types of stainless steel. Therefore, stainless steel is classified as 

• a compound
• an element 
• a mixture
• a substance

Which statement explains why increasing the temperature increases the rate of a chemical reaction, while other conditions remain the same?  

• The reacting particles have less energy and collide less frequently.
• The reacting particles have less energy and collide more frequently.
• The reacting particles have more energy and collide less frequently.
• The reacting particles have more energy and collide more frequently.

 An open flask is half filled with water at 25°C. Phase equilibrium can be reached after 

• more water is added to the flask
• the flask is stoppered
• the temperature is decreased to 15°C
• the temperature is increased to 35°C