Answer:
a . francium
Explanation:
because it is most metaliv and strongest metal
<u>Answer:</u> The enthalpy of formation of HCN(g) is 135.1 kJ/mol
<u>Explanation:</u>
Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles.
The equation used to calculate enthalpy change is of a reaction is:
![\Delta H^o_{rxn}=\sum [n\times \Delta H_f_{(product)}]-\sum [n\times \Delta H_f_{(reactant)}]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H_f_%7B%28product%29%7D%5D-%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H_f_%7B%28reactant%29%7D%5D)
For the given chemical reaction:

The equation for the enthalpy change of the above reaction is:
![\Delta H_{rxn}=[(2\times \Delta H_f_{(HCN(g))})+(6\times \Delta H_f_{(H_2O(g))})]-[(2\times \Delta H_f_{(NH_3(g))})+(3\times \Delta H_f_{(O_2(g))})+(2\times \Delta H_f_{(CH_4(g))})]](https://tex.z-dn.net/?f=%5CDelta%20H_%7Brxn%7D%3D%5B%282%5Ctimes%20%5CDelta%20H_f_%7B%28HCN%28g%29%29%7D%29%2B%286%5Ctimes%20%5CDelta%20H_f_%7B%28H_2O%28g%29%29%7D%29%5D-%5B%282%5Ctimes%20%5CDelta%20H_f_%7B%28NH_3%28g%29%29%7D%29%2B%283%5Ctimes%20%5CDelta%20H_f_%7B%28O_2%28g%29%29%7D%29%2B%282%5Ctimes%20%5CDelta%20H_f_%7B%28CH_4%28g%29%29%7D%29%5D)
We are given:

Putting values in above equation, we get:
![-870.8=[(2\times \Delta H_f_{(HCN(g))})+(6\times (-241.8))]-[(2\times (-80.3))+(3\times (0))+(2\times (-74.6))]\\\\\Delta H_f_{(HCN(g))}=135.1kJ/mol](https://tex.z-dn.net/?f=-870.8%3D%5B%282%5Ctimes%20%5CDelta%20H_f_%7B%28HCN%28g%29%29%7D%29%2B%286%5Ctimes%20%28-241.8%29%29%5D-%5B%282%5Ctimes%20%28-80.3%29%29%2B%283%5Ctimes%20%280%29%29%2B%282%5Ctimes%20%28-74.6%29%29%5D%5C%5C%5C%5C%5CDelta%20H_f_%7B%28HCN%28g%29%29%7D%3D135.1kJ%2Fmol)
Hence, the enthalpy of formation of HCN(g) is 135.1 kJ/mol
The description which accurately represents a water molecule is slightly negative oxygen pole, slightly positive hydrogen poles.
Water is a polar molecule. This means that the molecule has a dipole moment.
The polarity of water arises from the difference in electronegativity between hydrogen and oxygen.
Hence, in water molecule, oxygen is slightly negative and hydrogen is slightly positive thereby resulting in a dipole.
Learn more: brainly.com/question/10904296
Answer:
rain sleet ir snow si it has to be harsh
Answer:
1.4 g/cm³
Step-by-step explanation:
1. Calculate the <em>volume of the block</em>
V = lwh
<em>Data:
</em>
l = 150 cm
w = 0.20 m
h = 6.0 mm
(a) Convert all units to a <em>common base
</em>
w = 0.20 m × (100 cm/1 m)
w = 20 cm
h = 6.0 mm × (1 cm/10 mm)
h = 0.6 cm
<em>Calculation:
</em>
V = lwh
V = 150 × 20 × 0.60
V = 1800 cm³
2. Calculate the <em>density
</em>
Density = mass/volume
<em>Data:
</em>
m = 2.5 kg
<em>Calculation:
</em>
m = 2.5 kg Convert to grams
m = 2.5 kg × (1000 g/1 kg)
m = 2500 g
Density = 2500 g/1800 cm³
Density = 1.4 g/cm³