Answer:
D. Strong nuclear force, electrostatic force, weak nuclear force, gravitational force
The blank is filled by Na₂SO₄, and the complete equation for the double displacement reaction is:
Na₂SO₄ + BaCl₂ = BaSO₄ + 2 NaCl
<h3>What is a double displacement reaction?</h3>
It is a reaction in which both reactants exchange anions and cations.
Let's consider the following incomplete double displacement reaction.
_____ + BaCl₂ = BaSO₄ + 2 NaCl
If we compare the left and right sides, we can see that the missing ions in the left side are Na⁺ and SO₄²⁻. Thus, the missing compound is Na₂SO₄. The complete equation is:
Na₂SO₄ + BaCl₂ = BaSO₄ + 2 NaCl
Learn more about double displacement here: brainly.com/question/23918356
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Answer:

Explanation:
In this question, we wish to find the missing nuclei for the equation:

In order to find the missing species, we need to use the charge and mass balance law. That is, the mass should be conserved: the total mass on the left-hand side with respect to the arrow should be equal to the total mass on the right-hand side with respect to the arrow:

Notice from here that:

So far we know that the mass of X is 4. Similarly, we apply the law of charge conservation. The total charge should be conserved:

From here:

We have a particle:

Looking at the periodic table, an atom with Z = 2 corresponds to helium. This can also be written as an alpha particle:

D. They act on a specific type of substrate in a reaction
Hope this helps!