Explanation

Elements having zero nuclear spin cannot be directly determined by NMR (Nuclear Magnetic Resonance) spectroscopy because NMR relies on the detection of signals from nuclei with non-zero nuclear spin.

Explanation

The metal that is most active is the one that can displace other metals from their salts. Based on the equations provided:

• Ni can displace Pb from Pb(NO3)2, so Ni is more active than Pb.
• Ni cannot displace Ag from AgNO3 (no reaction), so Ag is less active than Ni.
• Cu cannot displace Ag from AgNO3 (no reaction), so Ag is less active than Cu.

Therefore, the order of reactivity is: Ni > Pb > Cu > Ag

So, Ni is the most active metal among the options.

Explanation

The metal ions of transition metals are paramagnetic. The magnetic moment towards magnetic field is greatest of Fe^+3.

Explanation

In SF6 (sulfur hexafluoride), the central sulfur atom is bonded to six fluorine atoms in an octahedral arrangement. This results in two types of bond angles:

• The F-S-F bond angles in the equatorial plane are 90°
• The F-S-F bond angles between the equatorial and axial fluorine atoms are 180°

Explanation

• First, we calculate the number of moles of acetic acid used:

Number of moles of acetic acid = mass of acetic acid / molar mass of acetic acid

Number of moles of acetic acid = 30 g / 60 g/mol = 0.5 moles

Since the reaction is 1:1 between acetic acid and ethyl acetate, the number of moles of ethyl acetate produced is also 0.5 moles.

• Now, we can calculate the theoretical yield of ethyl acetate:

Theoretical yield of ethyl acetate = number of moles of ethyl acetate * molar mass of ethyl acetate

Theoretical yield of ethyl acetate = 0.5 moles * 88 g/mol = 44 grams

• Now, we can calculate the percentage yield:

Percentage yield = (actual yield / theoretical yield) * 100%

Percentage yield = (40 g / 44 g) * 100%

Percentage yield ≈ 90.9%

So, the percentage yield of the ester is approximately 90.9%.

Explanation

Polymers that soften on heating and harden when cooled are called thermoplastics.

Explanation

The concentration of A after 29 seconds is approximately 0.15 M.

Explanation

• The original sentence "Could you help me, please?" is in the active voice, where the subject ("you") performs the action ("help").
• When changing to the passive voice, the object ("me") becomes the subject, and the original subject ("you") becomes the agent of the action, but is often omitted in polite requests.
• Thus, the passive voice form is "Could I be helped, please?"

Explanation

We must try to understand his momentary aberration for Hyder has undergone more strain and anxiety than any among us.

Explanation

• The mass spectrum of CH3Br (methyl bromide) shows two peaks at m/z values of 94 and 96, corresponding to the molecular ions [CH3Br]+.
• These peaks are due to the natural abundance of bromine isotopes, 79Br and 81Br, which are present in a ratio of approximately 3:1.
• As a result, the peak at m/z 94 ([CH379Br]+) is about 3 times more intense than the peak at m/z 96 ([CH381Br]+).