SZABMU MDCAT 2023 past paper, Code C

Answer: D. 400J

The electric energy supplied to the heater is calculated using the formula $E = V^2t/R$. Plugging in the given values of voltage (V=20V), time (t=10s), and resistance (R=10 ohm), we get $E = (20^2 * 10) / 10 = 400 J$. A common mistake might be to use the formula $E = VIt$, which would require calculating the current first ($I = V/R = 20/10 = 2A$), leading to $E = 20 * 2 * 10 = 400 J$.

Answer: C. Isobaric process

The correct answer is C because "baric" in isobaric refers to pressure. Therefore, an isobaric process is one where pressure remains constant. An isochoric process has constant volume, an adiabatic process has no heat exchange, and an isothermal process has constant temperature, making them incorrect in this context.

Answer: C. Paschen and Brakett

The Paschen series (n=3 to n>3) and Brackett series (n=4 to n>4) of the hydrogen spectrum fall within the infrared region. The Lyman series is in the ultraviolet, while the Balmer series extends into the visible spectrum.

Answer: A. a = rα

The linear acceleration ($a$) of a point on a rotating object is directly proportional to its distance from the axis of rotation ($r$) and the angular acceleration ($\alpha$). This relationship is expressed by the formula $a = r\alpha$. Option B is incorrect because it incorrectly divides by angular acceleration, and options C and D involve incorrect powers of $r$ or $\alpha$.

Answer: B. Symplast

Water moves through plasmodesmata when it travels from one cell's cytoplasm to another. This continuous cytoplasmic pathway, interconnected by plasmodesmata, is known as the symplast pathway. The apoplast pathway, in contrast, involves water movement through cell walls and intercellular spaces, not directly through the cytoplasm.

Answer: D. Class Mammalia

Negative feedback mechanisms are crucial for maintaining homeostasis, and these advanced regulatory systems are most highly developed in mammals due to their complex physiological needs, such as endothermy. While other classes exhibit some homeostatic control, mammals possess the most sophisticated and widespread use of negative feedback loops for temperature regulation, blood glucose levels, and other vital functions. Option D is correct because mammals exhibit the most comprehensive and characteristic use of negative feedback mechanisms for maintaining internal stability.

Answer: C. NaOH + CaO

Benzene is prepared in the lab by the decarboxylation of sodium benzoate using a mixture of sodium hydroxide and calcium oxide. This mixture acts as a strong base and dehydrating agent, facilitating the removal of the carboxyl group as sodium carbonate and yielding benzene. Option D, Na/Ether, is a common reagent for the Wurtz reaction, which involves the coupling of alkyl halides.

Answer: B. -COOH > C₆H₅OH > H₂O > -OH

Carboxylic acids are the strongest acids due to the resonance stabilization of the carboxylate anion. Phenol is more acidic than water because the phenoxide ion is resonance-stabilized, unlike the alkoxide ion formed from alcohols. Alcohols are generally less acidic than water because the negative charge on the alkoxide ion is localized on the oxygen atom, making it less stable than the hydroxide ion.

Answer: C. l = n-1

The azimuthal quantum number ($l$) can have values ranging from 0 up to $n-1$, where $n$ is the principal quantum number. Therefore, the relationship $l = n-1$ correctly describes the maximum possible value of $l$ for a given $n$. Option B, $l=n-2$, describes a valid but not the maximum value of $l$.

Answer: B. At

We use "at" to give a price or rate: sold at a pound, bought at a discount, sold at over a pound. "Sold off" means got rid of something cheaply, and it would not take "over a pound" after it. "Out" and "in" do not go with a price at all.