Answer:
b. a new gas is observed in the form of bubbles
Explanation:
The only statement that was evidence of a chemical reaction is a new gas is observed in the form of bubbles Any time a new substance is created, a chemical reaction has taken place.
Answer:
The number of protons also determines the identity of the element. ... Since the atom is electrically neutral, the number of electrons must equal the number of protons.
Answer:
Displaced
Explanation:
A convenient way to measure the volume of an object is to measure the volume of a solid is to immerse the solid into water.
When a solid is immersed in water, it displaces some volume of water. This volume of water displaced is the same as the volume of the object.
For instance, if the volume of water in a measuring cylinder was 25 ml and i added a stone which made the water in the measuring cylinder to rise to 70 ml, it simply means that the volume of the object is 70 ml - 25 ml = 45 ml
Answer: The chemical equation for the formation one mole of 
from its elements in their standard states is 
Explanation:
The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states.
The chemical equation for the formation one mole of from its elements in their standard states is:
where (s) represents solid state and (g) represents gaseous state.
Molar concentration is the number of Na₂SO₄ moles that are dissolved in 1 L of solution.
when 625 mL is added to 344 mL of Na₂SO₄, then the number of moles that are dissolved in 344 mL remains constant but volume increases. Therefore concentration now decreases.
Molar concentration of Na₂SO₄ is 1.675 M
the number of Na₂SO₄ moles in 1000 mL - 1.675 mol
then number of Na₂SO₄ moles in 344 mL - 1.675 mol / 1000 x 344 = 0.5762 mol
the new volume - 344 mL + 625 mL = 969 mL
concentration = number of moles / volume
therefore new concentration = 0.5762 mol / 0.969 L = 0.595 mol/L
new concentration of Na₂SO₄ is 0.595 M
