UPSC NDA-1

31. In mitochondria, ATP synthesizing chemical reactions take place in the

In mitochondria, ATP synthesizing chemical reactions take place in the

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Outer membrane.
Matrix.
Inner membrane.
DNA of mitochondria.
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In mitochondria, ATP synthesizing chemical reactions, specifically oxidative phosphorylation, take place on the inner membrane.
The inner mitochondrial membrane contains the electron transport chain complexes and ATP synthase. The process of oxidative phosphorylation, which generates the vast majority of ATP in cellular respiration, involves creating a proton gradient across the inner membrane (protons pumped from the matrix to the intermembrane space) and then using the potential energy of this gradient as protons flow back into the matrix through ATP synthase, which catalyzes the synthesis of ATP from ADP and phosphate.
The matrix is where the Krebs cycle occurs, producing electron carriers (NADH and FADH₂) that feed electrons into the electron transport chain located on the inner membrane. The outer membrane is permeable to small molecules and ions. Mitochondrial DNA (mtDNA) is located in the matrix and encodes some of the proteins required for mitochondrial function, but not the main ATP synthesizing reactions themselves.

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32. Movement of materials to different parts of cytoplasm and nucleus is g

Movement of materials to different parts of cytoplasm and nucleus is generally carried out by

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Ribosomes.
Mitochondria.
Lysosomes.
Endoplasmic reticulum.
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Movement of materials to different parts of cytoplasm and nucleus is generally carried out by the Endoplasmic reticulum.
The endoplasmic reticulum (ER) is a vast network of interconnected membranes extending throughout the cytoplasm of eukaryotic cells. It forms a continuous network with the outer membrane of the nuclear envelope, providing channels and pathways for the transport of molecules within the cell. Proteins synthesized on ribosomes attached to the rough ER are often transported within the ER lumen, and lipids synthesized in the smooth ER can also move through the ER network. The ER system is crucial for intracellular transport.
Ribosomes synthesize proteins but do not transport materials within the cell’s internal network. Mitochondria are involved in energy production. Lysosomes are involved in degradation and recycling. While vesicles budding from the ER and Golgi are involved in transport to other organelles or outside the cell, the basic network for internal movement of materials through the cytoplasm and towards the nucleus is largely provided by the ER.

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33. According to the New Cartesian Sign Convention, which one of the follo

According to the New Cartesian Sign Convention, which one of the following is correct in respect of the formula $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$, where symbols have their usual meanings?

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It applies only to spherical mirrors.
It applies only to spherical lenses.
It applies to spherical mirrors as well as spherical lenses.
It is an invalid formula.
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The formula $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$ is the standard equation that applies to both spherical mirrors and spherical lenses when used with the New Cartesian Sign Convention.
For spherical mirrors, this is known as the mirror formula. For spherical lenses, it is known as the thin lens formula. The New Cartesian Sign Convention provides a consistent set of rules for assigning positive or negative signs to object distance ($u$), image distance ($v$), and focal length ($f$), ensuring that the formula holds true for both real and virtual images/objects and for both converging and diverging mirrors/lenses.
While the formula form is the same, the application of the sign convention and the meaning of $f$ (positive for converging, negative for diverging) correctly distinguish between types of mirrors and lenses. Other related formulas, like the magnification formula ($m = \frac{h’}{h} = -\frac{v}{u}$ for mirrors and $m = \frac{h’}{h} = \frac{v}{u}$ for lenses, with the sign convention applied), are also used in conjunction with these fundamental formulas.

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34. Which of the following are the primary colours of light ?

Which of the following are the primary colours of light ?

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Yellow, Red and Green
Blue, Red and Green
Violet, Red and Yellow
Indigo, Violet and Green
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The primary colours of light are Blue, Red, and Green.
Primary colours of light are those colours that cannot be produced by mixing other colours of light, and from which a wide range of other colours can be created by mixing. In additive colour mixing (mixing of light), the primary colours are Red, Green, and Blue (RGB). This is the basis for how colours are displayed on screens (TVs, monitors, phones).
The combination of the three primary colours of light in equal proportions results in white light. Combining any two primary colours produces a secondary colour: Red + Green = Yellow, Red + Blue = Magenta, Green + Blue = Cyan. These secondary colours of light are the primary colours of pigment (in subtractive mixing).

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35. Which one of the following colours may be obtained by combining green

Which one of the following colours may be obtained by combining green and red colours ?

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Blue
Magenta
Pink
Yellow
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By combining green and red colours of light, the colour yellow is obtained.
This refers to additive colour mixing, which is relevant for light. The primary colours of light are Red, Green, and Blue (RGB). When these primary colours are mixed in different proportions, they produce other colours. Combining two primary colours results in a secondary colour: Red + Green = Yellow, Red + Blue = Magenta, Green + Blue = Cyan.
Subtractive colour mixing, relevant for pigments and dyes, works differently. The primary colours in subtractive mixing are Cyan, Magenta, and Yellow (CMY). Combining these primaries removes wavelengths of light. For example, mixing yellow and magenta paints typically results in red.

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36. The image we see in plane mirror is

The image we see in plane mirror is

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real and thus can be photographed.
virtual and nearer than the object.
virtual and is laterally inverted.
real but cannot be photographed.
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The image we see in a plane mirror is virtual and is laterally inverted.
A virtual image is one where the light rays appear to diverge from the image location but do not actually pass through it. Virtual images cannot be projected onto a screen. A plane mirror always forms a virtual image. Lateral inversion means that the image is reversed from left to right relative to the object. The image formed by a plane mirror is also upright and the same size as the object, and located at the same distance behind the mirror as the object is in front.
Real images are formed when light rays actually converge at the image location, and they can be projected onto a screen (and thus photographed directly). Examples include images formed by converging lenses in cameras or projectors, or by concave mirrors when the object is placed outside the focal point.

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37. Numerically two thermometers, one in Fahrenheit scale and another in C

Numerically two thermometers, one in Fahrenheit scale and another in Celsius scale shall read same at

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– 40°
0°
– 273°
100°
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The temperature at which both the Fahrenheit and Celsius scales read the same numerical value is -40°.
To find the point where the two scales read the same, we set the temperature in Fahrenheit ($T_F$) equal to the temperature in Celsius ($T_C$) and use the conversion formula: $T_F = T_C$. Let this common temperature be $x$. The conversion formula from Celsius to Fahrenheit is $T_F = T_C \times \frac{9}{5} + 32$. Substituting $x$ for both $T_F$ and $T_C$: $x = x \times \frac{9}{5} + 32$. Solving for $x$: $x – \frac{9x}{5} = 32 \implies \frac{5x – 9x}{5} = 32 \implies \frac{-4x}{5} = 32 \implies -4x = 160 \implies x = \frac{160}{-4} = -40$. Thus, -40°C is equal to -40°F.
Water freezes at 0°C (32°F) and boils at 100°C (212°F). These fixed points are different on the two scales, but there is one point where they intersect.

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38. Which one of the following is the lowest possible temperature ?

Which one of the following is the lowest possible temperature ?

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0° Celsius
– 073° Celsius
– 173° Celsius
– 273° Celsius
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The lowest possible temperature is absolute zero, which is defined as 0 Kelvin. On the Celsius scale, 0 Kelvin corresponds to approximately -273.15° Celsius.
Absolute zero is the theoretical lowest possible temperature where particles have minimal vibrational motion. The Celsius scale is related to the Kelvin scale by the formula $T(K) = T(°C) + 273.15$. Therefore, 0 K = $T(°C) + 273.15$, which gives $T(°C) = -273.15$. Among the given options, -273° Celsius is the closest value to absolute zero.
The Fahrenheit scale also has a zero point, but it is not absolute zero. The relationship between Celsius and Fahrenheit is $T(°F) = T(°C) \times \frac{9}{5} + 32$. Absolute zero (-273.15°C) is approximately -459.67°F.

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39. Which of the following sets of elements has the same valency ?

Which of the following sets of elements has the same valency ?

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Na, Mg, Ca
Na, Mg, Al
Mg, Ca, K
Mg, Ca, Ba
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The set of elements Mg, Ca, and Ba has the same valency. All three elements belong to Group 2 (Alkaline Earth Metals) of the periodic table.
Elements in the same group of the periodic table typically have the same number of valence electrons and thus exhibit similar chemical properties, including the same common valency. Magnesium (Mg), Calcium (Ca), and Barium (Ba) are all in Group 2, and they tend to lose their two valence electrons to form ions with a +2 charge. Their valency is 2.
In option A, Na (Group 1, valency 1), Mg (Group 2, valency 2), Ca (Group 2, valency 2). In option B, Na (valency 1), Mg (valency 2), Al (Group 13, valency 3). In option C, Mg (valency 2), Ca (valency 2), K (Group 1, valency 1). Only option D shows elements exclusively from the same group (Group 2) with the same characteristic valency.

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40. Which one of the following statements about dihydrogen (H₂) is not cor

Which one of the following statements about dihydrogen (H₂) is not correct ?

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H₂ is lighter than air and insoluble in water.
H₂ is inert at room temperature due to high H – H bond dissociation enthalpy.
H₂ reacts with alkali metals at high temperature to yield metal hydrides.
A mixture of NO₂ and H₂ is known as Syngas.
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The statement “A mixture of NO₂ and H₂ is known as Syngas” is not correct. Syngas (synthesis gas) is primarily a mixture of carbon monoxide (CO) and hydrogen (H₂).
Syngas is a fuel gas mixture that can be produced from various carbon-containing materials like natural gas, coal, biomass, or plastic waste. It is used as a fuel or as an intermediate for the production of other chemicals like methanol and ammonia. Nitrogen dioxide (NO₂) is a toxic gas primarily associated with air pollution.
Dihydrogen (H₂) is indeed lighter than air and practically insoluble in water. Its high H–H bond dissociation enthalpy (435 kJ/mol) makes it quite stable and inert at room temperature. At high temperatures, it reacts with alkali metals (like Na, K, Li) to form ionic hydrides (e.g., 2Na + H₂ → 2NaH), where hydrogen acts as an anion (H⁻).

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