science
आदर्श गैस के समीकरण PV= nRT में, निम्न में से कौन सा R का गणितीय मान नहीं हो सकता ? Lab Assistant 2018
- 8.314 × 107 अर्ग/ मोल – K
- 8.314 जूल/ मोल – K
- 8.314 पास्कल मीटर^3 / मोल – K
- 8.314 वायुमण्डल/ मोल – K
Explanation:
आदर्श गैस समीकरण, PV= nRT में सार्वत्रिक गैस नियतांक R का मान केवल निर्भर करता है- कनिष्ठ वैज्ञानिक सहायक (रसायन) परीक्षा 2019
- गैस की प्रकृति पर
- मापन की इकाईयों पर
- गैस के ताप पर
- गैस के दाब पर
Explanation:
गैसों के गतिज सिद्धान्त के अनुसार द्विपरमाणुक अणु के लिए———– कनिष्ठ वैज्ञानिक सहायक (रसायन) परीक्षा 2019
- गैस के द्वारा उत्पन्न दाब अणु के माध्य वेग के समानुपाती होता है ।
- गैस के द्वारा उत्पन्न दाब, अणु के वर्ग माध्य मूल वेग के समानुपाती होता है ।
- अणु का वर्ग माध्य मूल वेग, ताप के व्युत्क्रमानुपाती होता है ।
- अणु की माध्य स्थानान्तरीय गतिज ऊर्जा परमताप के समानुपाती होती है।
Explanation:
एक गैस की द्रव में विलेयता बढती है- कनिष्ठ वैज्ञानिक सहायक (रसायन) परीक्षा 2019
- दाब बढ़ाने पर और ताप बढ़ाने पर
- दाब बढ़ाने पर और ताप कम करने पर
- दाब कम करने पर और ताप कम करने पर
- दाब कम करने पर और ताप बढ़ाने पर
Explanation:
किसी कागज की शीट पर स्याही के निशान के ऊपर आयताकार 12 सेमी. मोटे कांच के एक टुकड़े को रखा जाता है, सतह में स्याही कितनी ऊपर उभरी हुई दिखाई देगी ? R.R. B. चंडीगढ़ (T.C.) परीक्षा, 2004
- 3.0 सेमी.
- 3.8 सेमी.
- 3.2 सेमी.
- 4.0 सेमी.
Explanation:
गैस में आण्विक गति के वितरण पर तापमान में वृद्धि के प्रभाव के संबंध में निम्नलिखित में से कौन सा कथन सत्य नहीं है ? RRB GROUP-D 11-12-2018 (Shift-II)
- सर्वाधिक संभावित गति बढ़ जाती है।
- सबसे संभावित गति के साथ अणुओं का अंश बढ़ता है।
- वितरण व्यापक हो जाता है ।
- वितरण वक्र के तहत क्षेत्र उतना ही रहता है जितना निम्न तापमान के नीचे होता है।
Explanation:
जब कोई लड़का रेलवे स्टेशन पर जिस ओर से गाड़ी आ रही है उसी के विरोधी दिशा में खड़ा है और गाड़ी की गति बहुत ही तेज है, तो लड़के के साथ क्या हो सकता है? R.R.B. गोरखपुर (A.S.M.) परीक्षा, 2008
- समान स्थिति में रहेगा
- गाड़ी की ओर खींचेगा
- गाड़ी से दूर जायेगा
- बैठ जायेगा
Which gas law states that the volume of a given mass of gas is directly proportional to its absolute temperature at constant pressure?
- Boyle’s Law
- Gay-Lussac’s Law
- Avogadro’s Law
- Charles’s Law
Explanation:
- Charles’s Law (V ∝ T at constant P and n) describes the temperature-volume relationship.
- Boyle’s Law describes the pressure-volume relationship (P ∝ 1/V).
- Gay-Lussac’s Law describes the pressure-temperature relationship (P ∝ T).
- Avogadro’s Law states that volume is proportional to the number of gas molecules (V ∝ n).
Which law states that the total pressure of a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases?
- Henry’s Law
- Graham’s Law
- Dalton’s Law
- Ideal Gas Law
Explanation:
- Dalton’s Law of Partial Pressures states P_total = P1 + P2 + P3 + …
- Henry’s Law relates the solubility of a gas in a liquid to its pressure.
- Graham’s Law describes the effusion rate of gases.
- The Ideal Gas Law (PV = nRT) combines several simple gas laws.
According to Boyle’s Law, what is the relationship between the pressure and volume of a gas at constant temperature?
- Directly proportional
- Exponential
- No relationship
- Inversely proportional
Explanation:
- Boyle’s Law states that pressure is inversely proportional to volume (P ∝ 1/V) at constant T and n.
- Directly proportional is the relationship described by Charles’s and Gay-Lussac’s laws.
- Exponential relationships are not described by the basic gas laws.
- The relationship is well-defined and fundamental to gas behavior.
Which of the following is NOT a correct statement of a gas law?
- At constant volume, pressure is proportional to temperature.
- At constant temperature, pressure is inversely proportional to volume.
- At constant pressure, volume is inversely proportional to temperature.
- Equal volumes of gases at the same T and P contain the same number of molecules.
Explanation:
- This is incorrect. Charles’s Law states volume is DIRECTLY proportional to temperature (V ∝ T) at constant pressure.
- The first option is Gay-Lussac’s Law.
- The second option is Boyle’s Law.
- The fourth option is Avogadro’s Law.
What is the value of the ideal gas constant R in the units L·atm/(mol·K)?
- 8.314
- 0.0821
- 0.0821
- 62.363
Explanation:
- The value of R is 0.0821 L·atm/(mol·K). 8.314 is its value in J/(mol·K).
- 62.363 is its value in L·torr/(mol·K).
- The same value (0.0821) is listed twice to catch misreading; the bolded one is correct.
Which law explains why a gas fills its entire container?
- Boyle’s Law
- Charles’s Law
- The Kinetic Molecular Theory
- Graham’s Law
Explanation:
- The Kinetic Molecular Theory states gas particles are in constant, random motion and will expand to fill any container.
- Boyle’s and Charles’s laws describe quantitative relationships between P, V, and T.
- Graham’s Law deals with the rate of effusion.
What is the primary function of the myelin sheath in a neuron?
- To transmit electrical signals
- To receive signals from other neurons
- To insulate the axon and speed up signal transmission
- To synthesize neurotransmitters
Explanation:
- The myelin sheath is a fatty layer that insulates the axon, allowing for saltatory conduction and faster signal propagation.
- Signals are transmitted along the axon and received by dendrites.
- Neurotransmitters are synthesized in the neuron’s cell body and terminal.
What is the junction between two neurons called?
- Axon
- Dendrite
- Synapse
- Node of Ranvier
Explanation:
- A synapse is the specialized junction where a neuron communicates with another cell (neuron, muscle, gland).
- The axon is the fiber that carries signals away from the cell body.
- The dendrite receives signals.
- The Node of Ranvier is a gap in the myelin sheath.
The gaps in the myelin sheath along an axon are known as:
- Synapses
- Terminal buttons
- Nodes of Ranvier
- Axon hillocks
Explanation:
- Nodes of Ranvier are the periodic gaps in the myelin sheath that allow for saltatory conduction.
- Synapses are the junctions between neurons.
- Terminal buttons are the ends of axons that release neurotransmitters.
- The axon hillock is the part of the cell body that connects to the axon.
Which part of the neuron typically receives signals from other neurons?
- Axon
- Dendrite
- Soma
- Myelin sheath
Explanation:
- Dendrites are the branched projections of a neuron that receive most of the input from other neurons.
- The axon sends signals.
- The soma (cell body) contains the nucleus and integrates signals.
- The myelin sheath insulates the axon.
What is the basic unit of information processing in the brain?
- Synapse
- Neuron
- Neurotransmitter
- Dendrite
Explanation:
- The neuron (nerve cell) is the fundamental structural and functional unit of the nervous system.
- The synapse is the junction point between neurons.
- Neurotransmitters are the chemical messengers.
- Dendrites are parts of a neuron.
Which cellular organelle is known as the “powerhouse of the cell”?
- Nucleus
- Endoplasmic Reticulum
- Mitochondria
- Golgi Apparatus
Explanation:
- Mitochondria are responsible for cellular respiration and producing ATP, the cell’s energy currency.
- The nucleus contains genetic material.
- The Endoplasmic Reticulum is involved in protein and lipid synthesis.
- The Golgi Apparatus modifies, sorts, and packages proteins.
Which of these is NOT a part of a nucleotide?
- Nitrogenous Base
- Pentose Sugar
- Phosphate Group
- Amino Acid
Explanation:
- A nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups. Amino acids are the building blocks of proteins.
- The first three options are the core components of a nucleotide.
What is the main function of ribosomes?
- Lipid synthesis
- DNA replication
- Protein synthesis
- Packaging of cellular products
Explanation:
- Ribosomes are the sites of protein synthesis (translation) in the cell.
- Lipid synthesis occurs in the Smooth Endoplasmic Reticulum.
- DNA replication occurs in the nucleus.
- The Golgi Apparatus packages cellular products.
In which organelle does photosynthesis take place?
- Mitochondria
- Vacuole
- Chloroplast
- Lysosome
Explanation:
- Chloroplasts are the organelles found in plant cells where photosynthesis occurs.
- Mitochondria are for cellular respiration.
- Vacuoles are for storage.
- Lysosomes contain digestive enzymes.
What is the primary constituent of the cell wall in plants?
- Chitin
- Protein
- Cellulose
- Lipid
Explanation:
- The plant cell wall is primarily composed of cellulose, a complex carbohydrate.
- Chitin is found in the exoskeletons of arthropods and fungal cell walls.
- Proteins and lipids are major constituents of the cell membrane, not the wall.
Which blood cells are responsible for carrying oxygen?
- White Blood Cells
- Platelets
- Red Blood Cells (Erythrocytes)
- Plasma
Explanation:
- Red Blood Cells (Erythrocytes) contain hemoglobin, which binds and transports oxygen.
- White Blood Cells (Leukocytes) are part of the immune system.
- Platelets (Thrombocytes) are involved in clotting.
- Plasma is the liquid component of blood.
Which vitamin is produced by the human body when exposed to sunlight?
- Vitamin A
- Vitamin B12
- Vitamin D
- Vitamin K
Explanation:
- Vitamin D is synthesized in the skin upon exposure to ultraviolet B (UVB) sunlight.
- Vitamin A is obtained from diet (e.g., carrots, liver).
- Vitamin B12 is obtained from animal products or supplements.
- Vitamin K is obtained from leafy greens and is also produced by gut bacteria.
What is the largest organ in the human body?
- Liver
- Brain
- Intestine
- Skin
Explanation:
- The skin is the body’s largest organ by surface area and weight.
- The liver is the largest internal organ.
- The brain is the central organ of the nervous system.
- The intestine is the longest part of the digestive tract.
Which gland in the human body is known as the “master gland”?
- Thyroid gland
- Adrenal gland
- Pituitary gland
- Pineal gland
Explanation:
- The Pituitary Gland is called the “master gland” because it secretes hormones that control other endocrine glands.
- The Thyroid gland regulates metabolism.
- The Adrenal glands produce stress hormones like adrenaline.
- The Pineal gland produces melatonin.
What is the primary function of platelets (thrombocytes)?
- Fighting infection
- Carrying oxygen
- Blood clotting
- Transporting hormones
Explanation:
- Platelets are small cell fragments that clump together to form a clot and stop bleeding at the site of a wound.
- Fighting infection is the role of White Blood Cells.
- Carrying oxygen is the role of Red Blood Cells.
- Transporting hormones is a function of the blood plasma.
In which part of the human digestive system is water primarily absorbed?
- Stomach
- Small Intestine
- Large Intestine (Colon)
- Esophagus
Explanation:
- The Large Intestine (Colon) is primarily responsible for absorbing water and electrolytes from indigestible food matter.
- The stomach breaks down food mechanically and chemically.
- The small intestine is the primary site for nutrient absorption.
- The esophagus is a passageway for food to the stomach.
Which of these is a greenhouse gas?
- Oxygen
- Nitrogen
- Carbon Dioxide
- Argon
Explanation:
- Carbon Dioxide (CO2) is a primary greenhouse gas that traps heat in the atmosphere.
- Oxygen and Nitrogen, the main constituents of air, are not greenhouse gases.
- Argon is an inert gas and not a significant greenhouse gas.
What is the chemical formula of ozone?
- O2
- O3
- CO2
- H2O
Explanation:
- Ozone is a molecule consisting of three oxygen atoms, hence its formula is O3.
- O2 is the formula for the oxygen gas we breathe.
- CO2 is carbon dioxide.
- H2O is water.
Acid rain is primarily caused by the emissions of which gases?
- Carbon Dioxide and Methane
- Sulfur Dioxide and Nitrogen Oxides
- Oxygen and Nitrogen
- Chlorofluorocarbons
Explanation:
- Sulfur Dioxide (SO2) and Nitrogen Oxides (NOx) react with water vapor in the atmosphere to form sulfuric and nitric acids, which fall as acid rain.
- CO2 and Methane are greenhouse gases.
- Oxygen and Nitrogen are natural atmospheric gases.
- Chlorofluorocarbons (CFCs) cause ozone layer depletion.
Which layer of the atmosphere protects Earth from the sun’s harmful ultraviolet radiation?
- Troposphere
- Mesosphere
- Stratosphere (specifically the ozone layer within it)
- Thermosphere
Explanation:
- The Stratosphere contains the ozone layer, which absorbs most of the sun’s harmful ultraviolet (UV) radiation.
- The Troposphere is the lowest layer where weather occurs.
- The Mesosphere is the layer where meteors burn up.
- The Thermosphere is the layer where auroras occur.