Fischer, Newman and sawhorse projections

27 questions on Fischer, Newman and sawhorse projections from the Stereoisomerism chapter: 6 NEET level, 11 JEE Main, 10 JEE Advanced. Each one opens with its answer and solution.

• In a Fischer projection of a compound with one stereocentre, two groups attached to that centre are interchanged. The new projection represents the: NEET level
• A Fischer projection is rotated by 180 deg in the plane of the paper. The new projection represents: NEET level
• A Fischer projection of a chiral compound with one stereocentre is rotated by 90 deg in the plane of the paper. Without further changes, the redrawn projection ... NEET level
• Looking along the C2-C3 bond of butane in a staggered conformation, the two methyl groups are 60 deg apart. This conformation is called: NEET level
• In the Fischer projection of glyceraldehyde, CHO is at the top, CH2OH at the bottom, and on the middle carbon OH is on the right and H on the left. The CIP desc... NEET level
• L-Alanine is written as a Fischer projection with COOH at the top, CH3 at the bottom, and on the central carbon NH2 on the left and H on the right. Its CIP desc... NEET level
• A Fischer projection of lactic acid has CH3 at the top, COOH at the bottom, and on the central carbon H on the left and OH on the right. What is its CIP descrip... JEE Main level
• At one stereocentre of a Fischer projection, the top group is held fixed and the other three groups are cyclically permuted (left to right to bottom to left). T... JEE Main level
• A sawhorse projection of 2-bromobutane looks along the C2-C3 bond. The front carbon is C2: its three bonds point up (12 o'clock) to CH3, lower-left (8 o'clock) ... JEE Main level
• Assertion (A): the anti-staggered conformation of meso-2,3-dibromobutane is achiral. Reason (R): in the anti-staggered conformation the molecule has a centre of... JEE Main level
• Looking along the C2-C3 bond of 3-chlorobutan-2-ol, the back carbon is C3 and its groups are Cl at 6 o'clock, CH3 at 2 o'clock and H at 10 o'clock. The front ca... JEE Main level
• Use these interaction energies: eclipsed H/H 4.0 kJ/mol, eclipsed CH3/H 6.0 kJ/mol, eclipsed CH3/CH3 11 kJ/mol (no other terms). In a Newman projection along C2... JEE Main level
• An aldopentose is drawn as a Fischer projection with CHO at the top and CH2OH at the bottom. At C2, C3 and C4 the OH groups are all on the left. The sugar is: JEE Main level
• D-Erythrose is drawn with CHO at the top, CH2OH at the bottom, and OH on the right at both C2 and C3. D-Threose has OH on the left at C2 and on the right at C3.... JEE Main level
• Two staggered Newman projections of 2,3-dibromobutane, viewed along C2-C3, are given. Projection 1: front carbon has Br at 12, CH3 at 4 and H at 8 o'clock; rear... JEE Main level
• Which of the following operations on a Fischer projection leave the configuration of every stereocentre unchanged? JEE Main level
• Each of the following is a Fischer projection of 2,3-dihalobutane type compounds with CH3 at the top and bottom. Which represent meso compounds? JEE Main level
• A staggered Newman projection of 2-bromo-3-chlorobutane is viewed along C2-C3. The front carbon (C2) has CH3 at 12 o'clock, Br at 4 o'clock and H at 8 o'clock. ... JEE Advanced level
• A staggered Newman projection of butane-2,3-diol is viewed along C2-C3. The front carbon has OH at 12 o'clock, H at 4 o'clock and CH3 at 8 o'clock. The rear car... JEE Advanced level
• meso-Tartaric acid is drawn as a Fischer projection with COOH at the top and bottom, and both OH groups on the right (C2 and C3). The Fischer projection corresp... JEE Advanced level
• A compound is drawn as a Fischer projection with vertical chain C1 (CH3, top), C2, C3, C4 (CH3, bottom): C2 has left H and right Br; C3 has left H and right Cl.... JEE Advanced level
• L-Threonine is (2S,3R)-2-amino-3-hydroxybutanoic acid. It is drawn as a Fischer projection with COOH (C1) at the top and CH3 (C4) at the bottom. Which placement... JEE Advanced level
• Use these gauche interaction energies (dihedral 60 deg only, no other terms): Br/Br 4.0, Br/CH3 3.0, CH3/CH3 3.8 kJ/mol; any interaction involving H is zero. Th... JEE Advanced level
• The Newman projection of 2,3-dichlorobutane viewed along C2-C3 has front carbon (C2): Cl at 12, CH3 at 4, H at 8 o'clock, and rear carbon (C3): Cl at 6, CH3 at ... JEE Advanced level
• (2R,3R)-2,3-Dibromobutane is drawn as a Fischer projection with CH3 at the top and bottom. Which statements are correct? JEE Advanced level
• Which statements about the open-chain D-aldopentoses (CHO at the top, CH2OH at the bottom, OH on the right at C4 for the D-series) are correct? JEE Advanced level
• A Newman projection of a molecule CH3-CHCl-CHCl-CH3 (a specific stereoisomer) is drawn in one staggered conformation. Which statements are correct? JEE Advanced level