Answer to Question #118238 in General Chemistry for sepehr

Question

Which of the following is true about an element in its standard state?

It is always a solid.
Its enthalpy of formation is zero.
Pressure does not affect an element in its standard state.
It is always a single atom at SATP conditions.
Which of the following is a drawback of fossil fuels?

In Canada, they are primarily used to produce electricity.
They are difficult to distribute.
They produce greenhouse gases when combusted.
They comes in a variety of forms, from coal to oil to natural gas.
Which of the following is incorrect?

Biofuels, such as ethanol, can be used directly in most automobile engines.
Biofuels can be made from a variety of materials.
Biofuels come in a variety of forms.
Biofuels are derived from living things.
What is the efficiency of a device?

the ratio of total energy to useful energy
the ratio of useful energy produced to the total amount of energy expended
always close to 90 %
improves with a lower number

Answer 1

The correct statement about an element in its standard state:

Its enthalpy of formation is zero.

Which of the following is a drawback of fossil fuels?

They comes in a variety of forms, from coal to oil to natural gas.

Which of the following is incorrect?

Biofuels are derived from living things.

What is the efficiency of a device?

the ratio of useful energy produced to the total amount of energy expended