Which equation represents a double replacement reaction? A) 2 Na + 2 H2O → 2 NaOH + H2
B) CaCO3 → CaO + CO2
C) LiOH + HCl → LiCl + H2O
D) CH4 + 2 O2 → CO2 + 2 H2O

C) LiOH + HCl → LiCl + H₂O

General Formulas and Concepts:

Chemistry - Reactions

Explanation:

Step 1: Define

RxN A:   2Na + 2H₂O → 2NaOH + H₂

RxN B:   CaCO₃ → CaO + CO₂

RxN C:   LiOH + HCl → LiCl + H₂O

RxN D:   CH₄ + 2O₂ → CO₂ + 2H₂O

Step 2: Identify

RxN A:   Single Replacement Reaction

RxN B:   Decomposition Reaction

RxN C:   Double Replacement Reaction

RxN D:   Combustion Reaction

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3