There are 2 significant figures.
"Rule 3: Trailing zeros are significant if a decimal point is shown in the number, but may or may not be significant if no decimal point is shown."
hydrogen is the lightest element in the periodic table
Based on the chemical equation, to balance the given equation we should use 2 as a coefficients of HCl on reacatnt side of the reaction.
<h3>What is balanced equation?</h3>
Balanced chemical equations are those equation in which each entities are present in same amount on reactant side as well as on the product side of the chemical reaction.
Given chemical reaction is:
Zn + HCl → ZnCl₂ + H₂
In the above reaction equation is not balanced as number of chlorine and hydrogen atoms are not equal on both sides, so balanced equation will be:
Zn + 2HCl → ZnCl₂ + H₂
Hence we add 2 as a coefficient of HCl to balance the equation.
To know more about balance equation, visit the below link:
brainly.com/question/15355912
Answer is: 0,0095 mol of hydrogen gas will be produced in reaction.
Chemical reaction: Ca + 2HCl → CaCl₂ + H₂.
m(Ca) = 0,38 g.
n(H₂) = ?
n(Ca) = m(Ca) ÷ M(Ca).
n(Ca) = 0,38 g ÷ 40 g/mol
n(Ca) = 0,0095 mol.
from reaction: n(Ca) : n(H₂) = 1 : 1.
n(H₂) = n(Ca) = 0,0095 mol.
n - amount of substance.
Answer:
The standard enthalpy of formation of methanol is, -238.7 kJ/mole
Explanation:
The formation reaction of CH_3OH will be,
The intermediate balanced chemical reaction will be,
..[1]
..[2]
..[3]
Now we will reverse the reaction 3, multiply reaction 2 by 2 then adding all the equations, Using Hess's law:
We get :
..[1]
..[2]
[3]
The expression for enthalpy of formation of 
will be,
The standard enthalpy of formation of methanol is, -238.7 kJ/mole
