Billy and Susie heat a 78.9 g sample of Unobtanium at 18.0C. Using a lab burner, they burn propane and the unobtanium absorbs 13,240 J of heat untill the temperature reaches the melting point 109C. what is the specific heat of unobtanium

1.8 J/g·°C (2 sig.figs. per ΔT)

Explanation:

Given:

mass (m) = 78.9 grams

specific heat (c) = ?

Temp. Change (ΔT) = 109°C - 18°C = 91°C

Heat flow (q) = 13,240 Joules

q = m·c·ΔT => c = q/m·ΔT

∴c = 13,240J / 78.9g·91°C = 1.844 J/g·°C ≅ 1.8 J/g·°C (2 sig.figs. per ΔT)

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.