A physical change is when something don't permanently change
Mass number of an element write in bottom of it!
So, there 80 would be the mass number of ₈₀Br.
Hope this helps!
Answer
A *single covalent bond* is formed by sharing one pair of valence electrons.They are less reactive comparatviely and have a high bond length
A *double covalent bond* is formed by sharing two pairs of valence electrons.They are moderately reactive and have moderate bond length.
A *triple covalent bond* is formed by sharing three pairs of valence electrons.They are highly reactive and have a low bond length.
Answer: option <span>C. the total energy inside the calorimeter will decrease.
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Justification:
The answer is a direct application of the first law of thermodynamic (the law of conservation of energy).
By telling that the t<span>he calorimeter is sealed so that there is no heat exchanged between the contents of the container and the surrounding air, the first law of thermodynamics implies that the total energy inside the calorimeter will not change.
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<span>That statement, without adding any more is enough justification.
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Regarding, the other statements, you can show they are true:
<span>A.
the thermometer will show an increase in temperature.
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</span><span>Since the reaction is exothermic, the heat released will increase the temperature inside the sealed calorimeter,which, of course, is shown by the termometer.
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</span><span>B. The potential
energy of the products will be lower than that of the reactants.
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</span><span>In any exothermic reaction, the potential energy of the products is lower than that of the reactants, because the heat released is lost by the reactants when they react and transform into the products.
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</span><span>D. The water
increases in temperature as the reaction gives off heat</span>.
Sure. The heat cannot leave the sealed calorimeter, but the water inside the calorimeter will absorb that heat: the molecules of water will gain kinetic energy and so its temperature will be increase.
The correct answer is option 3. There are no attractive forces between the gas particles in an ideal gas. For an ideal gas to be achieved, the molecules are far from each other as possible where no attraction or collisions happen with each molecule.
