worth 100 points
this chart shows four atoms, labeled w, x, y, and z. these atoms can combine with each other to form molecules.

which atoms could join together to form a molecule of an element?

w and x

x and y

w and z

y and z

Option (c) is the correct answer.

Explanation:

A molecule is defined as a substance which can contain atoms of same or different elements that are chemically combined together.

For example, , , etc are molecules.

Whereas a compound is defined as a chemical specie which is made by the combination of different atoms in a fixed ratio by mass.

For Example, , etc. are compounds.

A compound will also be considered as a molecule but a molecule can never be considered as a compound.

And, a molecule of an element will always contain atoms of one type of element.

As in the given situation both W and Z atoms represent the same element, that is, oxygen.

Thus, we can conclude that W and Z atoms could join together to form a molecule of an element.

i believe the answer is a.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol