Answer:
Mass = 76.176 g
Explanation:
Given data:
Mass of lead(II) chloride produced = 62.9 g
Mass of lead(II) nitrate used = ?
Solution:
Chemical equation:
Pb(NO₃)₂ + 2HCl → PbCl₂ + 2HNO₃
Number of moles of lead(II) chloride:
Number of moles = mass/molar mass
Number of moles = 62.9 g/ 278.1 g/mol
Number of moles = 0.23 mol
Now we will compare the moles of lead(II) chloride with Pb(NO₃)₂ from balance chemical equation:
PbCl₂ : Pb(NO₃)₂
1 : 1
0.23 : 0.23
Mass of Pb(NO₃)₂:
Mass = number of moles × molar mass
Mass = 0.23 mol × 331.2 g/mol
Mass = 76.176 g
Answer: E) In a closed system, the total energy always remains constant.
Explanation: For every system, the law of conservation of energy is applicable which states that the energy of the system remains conserved. Energy can neither be created nor destroyed.
A closed system is one which can exchange energy with the surroundings but not mass. Thus if a system absorbs energy, the equivalent amount of energy is lost by surroundings, thus the total energy remains constant.
If a system loses energy, an equivalent amount of energy is gained by surroundings, thus the total energy remains constant.
<span>Answer:
p(def) = .05, p(good) = .95 , n = 20
Accept if x ≤ 2
P(x ≤ 2) = binomcdf(20, .05, 2) = .9245 0r 92.45%</span>
