Determine the empirical formula (EF) and molecular formula (MF) for the compound based on the provided elemental analyses. Based on its molecular formula, provide a plausible structure for the compound.

Mass Percent: C: 52.16% ; H: 7.88% ; N: 12.17% ; O: 27.79%

Molecular Weight: 115.131 g/mol

An unknown element has two stable isotopes, ⁵⁰X and ⁵¹X. The relative abundance of these isotopes is 0.25% and 99.75%, respectively. ⁵⁰X has an atomic mass of 49.947, while ⁵¹X has an atomic mass of 50.943. Determine the atomic mass and identity of X.

Show how pi orbitals are involved in the formation of pi bonds in the given molecules.

a. HCOOH
b. CH₃CN

Determine whether the σ bond or the π bond has the more effective orbital overlap in a carbon—carbon double bond.

Determine the number of electrons boron needs to gain or lose to achieve the noble gas electronic configuration and identify which noble gas it represents.

Based on their position on the periodic table, how many core and valence electrons do the following elements have?

(i) Arsenic

(ii) Antimony

(iii) Strontium

(iv) Beryllium

Determine the formal charge of the highlighted atom.

Change the following models to their corresponding skeletal structures.

Draw the Lewis structure of the given molecule and label the orbitals that overlap to form each bond, including carbon-to-hydrogen bonds and the bond angle around each nonhydrogen atom.

Write the appropriate Lewis structures for each of the following species NH₂NHCH₃, NHNCH₃, CH₃NH₃Cl and CH₃CH₂CN.

Draw the possible structures of cyclic compounds with the molecular formula C₄H₆ based on the degree of unsaturation. 

Give the relationship of the given pairs of molecules as the same compounds, constitutional isomers, or not isomers.

a. CH₃—CH=CH—CH₃ and CH₃—CH₂—CH=CH₂
b. CH₃—CH₂—CH₃ and CH₃—CH=CH₂
c. CH₂=CH—CH₂—CH₂—CH₂—CH₃ and CH₃—CH₂—CH=CH—CH₂—CH₃

Some pairs of structures are given at the end of the question. Recognize each of these pairs as different entities or resonance forms of the same compound.

Determine the appropriate hybridization of all indicated atoms in the following organic compounds.

Estimate the bond angles for the bonds mentioned below.

a. the H—C—N bond in HC≡N.

b. the C—C—N bond in CH₃CH₂NHCH₃.

Identify the oxygen atom that has the greater electron density and write the possible product when the given molecule reacts with H⁺.

Explain why pyrrole (129 °C) boils at a higher temperature than N-methyl pyrrole (112 °C).

Rank the molecules below from most to least water soluble.

Is the following hydroxyl group tertiary (3°), secondary (2°), or primary (1°)?

Upon completion of the reaction below, a small amount of unreacted amide was left dissolved in diethyl ether with the amine product. Suggest a scheme to remove the amine from the ether.

Predict the products expected from the electron pushing shown in the below-given compound.

Which of the reactants is the Lewis acid and which one is the Lewis base in the reaction given below?

Calculate the pH at which a compound has the concentration of its basic form 12 times greater than in its acidic form if the pK_a of the compound is 2.5.

The following is the structure of citric acid:

(i) Determine if the given structure is a carboxylic acid.

(ii) Compare the acidic strength of citric acid with lactic acid. Citric acid and lactic acid have pK_a values of 3.13 and 3.86, respectively.

Ethoxide cannot be used to deprotonate cyclohexane in a reaction that favors the formation of a carbanion. Explain why this is true.