NEET Unit Test - 1 - NEET MCQ

To find when the displacement (y) is zero, we set the displacement equation equal to zero and solve for t:

y = t² − t − 2

Setting y to zero:

0 = t² − t − 2

Now, we can factor the quadratic equation or use the quadratic formula to find the values of t when y is zero.

Factoring:

(t − 2)(t + 1) = 0

Setting each factor to zero:

t − 2=  0 or t + 1 = 0

Solving for t:

t = 2 or t = −1

Since time (t) cannot be negative in this context, we discard t = −1.

Therefore, the correct answer is (b) 2 s. The displacement is zero when t = 2 seconds.

T₁ = m(g + a₀) and T₂ = m(g – a₀)
∴ 

Displacement of each girl = 
Magnitude of displacement for each girl
For girl C, displacement = actual length of path.

Let θ be angle which the direction ofmakes with the

Since the block is moving down with constant speed, the net force acting on it along the plane is zero. This means the component of gravitational force down the incline is balanced by the frictional force. The force exerted by the plane on the block is the normal reaction, which depends on the angle of inclination. The normal force is given by:
N = mg cosθ
Thus, the force on the block by the plane is determined by the angle of inclination.

Newton's second law of motion relates force (F), mass (m), and acceleration (a) with the equation:

F = m ⋅ a

We can rearrange this equation to solve for mass (m):

m =  F/a

In this case, the force (F) is given as 90 N, and the acceleration (a) is given as 2.6 m/s².

m = 90N / 2.6m/s²

Calculating this gives:

m ≈ 34.615kg

So, the closest answer is (b) 34.6 kg.

Shortest path is along line AB.

If the boat crosses the river in 15 min 
⇒  = 4 km/hr   ∴ = 3 km/hr

We can use the following kinematic equation to relate initial velocity (u), final velocity (v), acceleration (a), and displacement (s):

v² = u² + 2as

In this scenario, the body starts at rest, so the initial velocity u is 0 m/s. The final velocity v is given as 8 m/s, and the displacement s is 32 m. We want to find the acceleration a.

8² = 0²+ 2a(32)

64 = 64a
a = 1 m/s²

So, the correct answer is (a) 1 m/s².

By conservation of momentum we get the speed of the bigger part let say, v = 1 x90 / 3
Hence we get v = 30
Thus the total KE of the system after collision is ½ (3 X 900 + 1 X 8100)
Thus KE = ½ (10800) = 5400
Now  if we apply WET to the system, as no external force has acted upon it, we get
W = ΔKE
= 5400 - 0
= 5.4 kJ

Eka-aluminium and gallium are the same elements because the properties of Eka-Aluminium are almost identical to the qualities of the gallium element. Eka-Aluminium is a chemical element that has nearly identical properties to the gallium element. The properties of the elements, such as their atomic mass, density, melting temperature, the formula of chloride, and the formula of oxide, are nearly identical to those anticipated by Mendeleev in his theory.

Group number eighteen. This suggests the presence of a Chalcogens element. Chalcogens elements are found in Group 16 of the modern periodic table, which is the most recent revision. Thus, the element having electronic configuration 2, 6 would be found in group 16 of the Modern Periodic Table, according to this definition. Therefore, option (C) is the most appropriate choice.

The correct answer is Potassium.
Key Points

• Potassium belongs to a group - (1) and period - (IV) of the periodic table. Hence among the given options, Potassium has a maximum atomic radius.
• Carbon and Nitrogen belong to the period - (II) of the periodic table and on the right side hence it is obvious that atomic radii of Carbon and Nitrogen are very much small than Sodium and Potassium.
• Sodium and Potassium belong to a group - (1) and  Potassium is placed below Sodium hence the atomic radius of Potassium more than Sodium.

Molar mass of O₂ = 32 g mol^-1
32 g of O₂ = 6.023 x 10²³ molecules
40 g of O₂ =  = 7.529 x 10²³ molecules
Mass of 6.023 x 10²³ molecules of CO₂ = 44 g
Mass of 7.529 x 10²³ molecules of CO₂

Correct Answer is A.

BF₃ - Trigonal planar with bond angle 120^º.
PCI₅ - Trigonal bipyramidal with bond angles 120^º and 90^º.

The correct answer is C-12.

• The International Union of Chemists selected the most stable carbon isotope (C-12) or ¹²C as the standard for comparison of the atomic masses of various elements.
  • The mass of C-12 is taken as a 12 atomic mass unit (standard).
  • A Carbon-12 contains six protons, six neutrons, and six electrons.

The correct answer is Chlamydomonas.

• Chlamydomonas is found in stagnant water and on damp soil as well as freshwater, seawater, and even in snow.
• About Chlamydomonas-
  • Class: Chlorophyceae
  • Order: Chlamydomonadales
  • Scientific name: Chlamydomonas
  • Phylum: Chlorophyta
  • Higher classification: Chlamydomonadaceae

Viroids are unique infectious agents made up solely of a short strand of RNA, without a protein coat, known for causing diseases in plants such as potato spindle tuber disease. This makes Option C correct. Option A incorrectly describes prions, not viroids; Option B is false as viroids are smaller than viruses and lack DNA; Option D describes lichens, not viroids.

The characteristic feature of sponges (phylum Porifera) among the options provided is the presence of Ostia. Ostia are tiny pores or openings on the body of a sponge that allow water to enter its central cavity, called the spongocoel. These ostia are responsible for the filtration of water, which is a vital process for sponges to obtain food and oxygen.

Cockroaches undergo paurometabolous development, characterized by nymphs that resemble miniature adults. These nymphs progressively become adults through multiple molts, growing in size and maturity with each stage. This type of development is typical of insects that do not undergo a complete metamorphosis involving a pupal stage (Option A). Options C and D are not applicable to cockroaches as they neither hatch as winged adults nor start their life cycle in aquatic environments.

The order generally ends with ales. Order being a higher category is the assemblage of families which exhibit a few similar characters.

Bacteria primarily reproduce through asexual reproduction, typically by binary fission. While bacteria can engage in processes like conjugation, which involves the transfer of DNA between bacteria, this is not considered true sexual reproduction because it does not involve the fusion of gametes. True sexual reproduction, as understood in eukaryotic organisms, does not occur in bacteria. And buds are produced in hydra.
Line in NCERT: Bacteria reproduce mainly by fission. Sometimes, under unfavourable conditions, they produce spores. They also reproduce by a sort of sexual reproduction by adopting a primitive type of DNA transfer from one bacterium to the other.

Cockroaches, like many other insects, possess an open circulatory system. This system is characterized by a limited network of blood vessels and a heart that pumps the hemolymph (blood) into the body cavity, where it directly bathes the organs. There is no distinction between blood and interstitial fluid in this type of system, unlike in closed circulatory systems.

(i) Diploblastic: Coelenterates (Cnidarians) are diploblastic as they have two germ layers: ectoderm and endoderm.

(ii) Triploblastic - Platyhelminthes to Chordates are triploblastic as they possess three germ layers: ectoderm, mesoderm, and endoderm.

(iii) Acoelomate - Platyhelminthes are classified as acoelomates.

(iv) Pseudocoelomate - Aschelminthes/Roundworms have a pseudocoelom.

(v) Eucoelomate - Annelids to Chordates have a true coelom.

Ciliated epithelium.Explanation:The inner surface of bronchioles and Fallopian tubes possess ciliated epithelium. In the respiratory tract cilia help to push mucus towards the pharynx. In Fallopian tube the cilia help to move an egg towards the uterus.

Platyhelminthes are triploblastic, acoelomate organism showing bilateral symmetry. Ctenophores have borads symmetry, are acoelomates having diploblastic organisation. In echinoderms, larvae have bilateral symmetry whiled add have radial symmetry. They are coelomates with triplobla organisation. Annelids are triploblastic, coelomaterorganism showing bilateral symmetry.