The gold leaf (not foil) is to give a sculpture or a painting appeal. Without it, it would discolour quicker.The gold leaf can be easily removed if needed to be.
28) All elements are made of atoms
29)Protons and Neutrons
-Electrons make up the outside of the Nucleus
Answer:

Explanation:
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In this case, since a change in science is widely known to be considered as a subtraction between the the final and initial values of two measured variables and is represented via Δ, here the final density is 5.43 g/mL and the initial one was 3.21 g/mL, therefore, the change in density is:

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Answer:
9.25
Explanation:
Let first find the moles of
and 
number of moles of
= 0.40 mol/L × 200 × 10⁻³L
= 0.08 mole
number of moles of
= 0.80 mol/L × 50 × 10⁻³L
= 0.04 mole
The equation for the reaction is expressed as:

The ICE Table is shown below as follows:

Initial (M) 0.08 0.04 0
Change (M) - 0.04 -0.04 + 0.04
Equilibrium (M) 0.04 0 0.04







for buffer solutions
since they are in the same solution


Answer : The pressure of the helium gas is, 1269.2 mmHg
Explanation :
To calculate the pressure of the gas we are using ideal gas equation:

where,
P = Pressure of
gas = ?
V = Volume of
gas = 210. mL = 0.210 L (1 L = 1000 mL)
n = number of moles
= 0.0130 mole
R = Gas constant = 
T = Temperature of
gas = 
Putting values in above equation, we get:


Conversion used : (1 atm = 760 mmHg)
Thus, the pressure of the helium gas is, 1269.2 mmHg