Answer:
Explanation:
Physical change is a temporary and reversible change in which the physical properties of the substance changes without altering the composition of the substance Eg Melting of ice while chemical change is a permanent and not so easily reversible change in which the identity of the substance is altered to produce one or more substances Eg Combustion
 
        
                    
             
        
        
        
Answer:
The answer to your question is: 6.55 x 10 ²³ atoms of Br
Explanation:
CH2Br2 = 37.9 g 
MW CH2Br2 = (12 x 1) + (2 x 1) + (80 x 2) = 174 g
                    174 g of CH2Br2 ------------------  160 g of Br2
                    37.9 g of CH2Br2   ---------------     x
                 x = 37.9 x 160/174 = 34.85 g of Br
                       1 mol of Br -----------------   160 g Br2
                          x              ----------------    174 g Be2
                x = 174 x 1 /160 = 1.088 mol of Br2
                 1 mol of Br -----------------  6.023 x 10 ²³ atoms
             1.088 mol of Br -------------    x
                     x = 1.088 x 6.023 x 10 ²³ / 1 = 6.55 x 10 ²³ atoms
 
        
             
        
        
        
To solve this problem, we must assume ideal gas behaviour so
that we can use Graham’s law:
vA / vB = sqrt (MW_B / MW_A)
where,
<span>vA = speed of diffusion of A  (HBR)</span>
vB = speed of diffusion of B (unknown)
MW_B = molecular weight of B (unkown)
MW_A = molar weight of HBr = 80.91 amu
 
We know from the given that:
vA / vB = 1 / 1.49
 
So,
1/1.49 = sqrt (MW_B / 80.91)
MW_B = 36.44 g/mol
 
Since this unknown is also hydrogen halide, therefore this
must be in the form of HX.
HX = 36.44 g/mol , therefore:
x = 35.44 g/mol
 
From the Periodic Table, Chlorine (Cl) has a molar mass of
35.44 g/mol. Therefore the hydrogen halide is:
HCl
 
        
             
        
        
        
Answer:
0.453 moles
Explanation:
The balanced equation for the reaction is:
2Fe(s) + 3O2(g)  ==>  2Fe2O3
From the equation,  mass of O2 involved = 16 x 2 x 3 = 96g
                                  mass of Fe2O3 involved = [(2x26) + 3 x 16] x 2
                                                                             = 100g
                 Therefore 96g of O2 produced 100g of Fe2O3
                                   32.2g of O2 Will produce   100x32.2/96
                                                    = 33.54g of Fe2O3
Converting it to mole using   number of mole = mass/molar mass
but molar mass of Fe2O3 = 26 + (16 X 3)
                                            = 74g/mole
Therefore number of mole of 33.54g of Fe2O3 = 33.54/74
                                                                            = 0.453 moles
 
        
             
        
        
        
The safety feature aimed at keeping nuclear radiation contained is steel-reinforced concrete.
<h3>What is nuclear power plant?</h3>
A nuclear power plant is a building with reactors that contain controlled nuclear reactions to produce energy.
Nuclear power plants are able to generate warm water by using atomic properties of matter  (i.e.,m the process of nuclear fission), which is in turn converted into steam to move turbines. 
The walls of nuclear power reactors are composed of steel-reinforced concrete in order to avoid radiation release.
In conclusion, the safety standard property that maintains nuclear radiation contained is steel-reinforced concrete.
Learn more about nuclear power plants here:
brainly.com/question/24295936
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