Amir wants to change this model to represent a different isotope of oxygen How could he make this change? А
add one green candy
B
rearrange the blue candies
C.
add one red candy
D
take away two blue candies

Option A. Add one green candy

Explanation:

From the question given above, the following data were obtained:

Red color => Proton

Green => Neutron

Blue => Electron

Isotopy is a phenomenon where by two or more elements have the same atomic number by different mass number due to the difference in the neutron number. The atoms involved are called isotopes.

From the above definition, isotope exist when the neutron number of the atoms are different with each having same atomic number (i.e proton number).

Thus, considering the question and the options given above, the only way to make a different isotope of oxygen is to add a green candy (i.e neutron).

your answer would be a. 12.5 kg

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