The answer is Strontium(Sr). The reactive increase from right to left. And this element has two valence electrons. So Rb is not correct. Then the very reactive metal is Sr.
Answer:
1.395J/g°C
Explanation:
The following were obtained from the question:
Q = 6527J
M = 312g
ΔT = 15°C
C =?
Q = MCΔT
C = Q/MΔT
C = 6527/(312 x 15)
C = 1.395J/g°C
The specific heat capacity of the substance is 1.395J/g°C
The best and most correct answer among the choices provided by your question is the first choice or letter A "<span>The chemical bonds of the products have more energy than the chemical bonds of the reactants."
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The term endothermic<span> process describes a process or </span>reaction<span> in which the system absorbs energy from its surroundings; usually, but not always, in the form of heat.</span>
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Answer:

Explanation:
In this problem, we need to convert
to km².
We know that,
1 km = 1000 m
⇒ 1 km² = 10⁶ m²
So,

So,
is equal to
.
Answer:
Lattice energy is <em>the energy required to convert a mole of ionic solid into its constituent ions in the gas phase</em>
Explanation:
Lattice energy is usually calculated by the Born-Haber cycle, from the affinity energies and sublimation ethalphy values. It is used as an estimation of the ionic energy strength between the ions in an ionic compound.
It is defined as the energy needed to broke 1 mol of a given ionic compound into its ions in the gaseous state. For example, the lattice energy for sodium chloride (NaCl) is the energy required to separate 1 mol of solid ionic compound (NaCl(s)) and produce the sodium and chlorine ions in the gas phase: Na⁺(g) and Cl⁻(g).