Answer: The correct option is (1).
Explanation:
Group 16 is the third-from-last column in the periodic table and is known as the oxygen family.
Members of this group include oxygen, sulfur, selenium, tellurium, and polonium.
Elements in Group 16 have 6 valence electrons in their outermost shell.
The electronic configuration of sulfur is 
.
Because sulfur belongs to Group 16, it has 6 valence electrons.
1) Calcium carbonate comprises 40.0% calcium by weight.
M(CaCO₃)=100.1 g/mol
M(Ca)=40.1 g/mol
w(Ca)=40.1/100.1=0.400 (which is 40.0%)!
2) The mass fraction mentioned is superfluous information.
3) The resulting solution is:
m(Ca)=1.2 g
m(CaCO₃)=M(CaCO₃)*m(Ca)/M(Ca)
m(CaCO₃)=100.1g/mol*1.2g/40.1g/mol=3.0 g
The amount of heat needed to elevate an object's temperature can be determined using the formula,
heat = mass x specific heat x (T2 - T1)
Thus, specific heat can be found with the following formula,
specific heat = heat / (mass x (T2 - T1))
By substituting,
specific heat = 645 J / ((28.4 g)(15.5 - - 11.6))
The calculated specific heat from the above equation is 0.838 J/g°C.
Initially, we calculate the moles of gas using the ideal gas law:
PV = nRT
n = PV / RT
n = (1.4 * 226.4) / (0.082 *(27 + 273.15))
n = 12.88
Next, we apply the given percentages to estimate the moles of helium:
Moles of helium = 0.655 * 12.88
Moles of helium = 8.44
We then use the formula:
Mass = moles * molar mass
Mass of helium = 8.44 * 4
Mass of helium = 33.76 grams.
Calculation yields 209.53. The molar concentration is calculated by moles divided by volume. Given the volume of 750 mL, which translates to 0.75 L, the moles of CuBr₂ can be determined as molar concentration multiplied by volume, resulting in 1.25 × 0.75 = 0.9375. Mole count is derived from the mass of CuBr₂ divided by its molecular mass. The molecular mass of CuBr₂ is computed as 63.5 + 80 × 2 = 223.5, where the mass of Cu is 63.5 and that of Br is 80. Consequently, the mass needed amounts to 223.5 × 0.9375 = 209.53 g.
