All questions of September Week 1 for NEET Exam

Ya it's B ....
Emerges from one side and enter from another side...

Cerium

La stands for Lanthanum, which is a member of the lanthanide series of elements in the periodic table. It has an atomic number of 57 and an electronic configuration of [Xe]5d1 6s2.

Achieving Noble Gas Configuration
To achieve a noble gas configuration, an element must have its outermost shell filled with electrons. The noble gases are stable because they have a filled outermost shell. Lanthanum can achieve this configuration by losing three electrons from its outermost shell.

Oxidation States
The oxidation state of an element is the charge that it carries when it forms a compound or ion. Lanthanum can form compounds in various oxidation states, including +2, +3, and +4.

In order to determine in which oxidation state La achieves noble gas configuration, we need to look at its electron configuration and determine how many electrons it needs to lose to achieve a filled outermost shell.

La3+ (Oxidation State of +3)
When Lanthanum loses three electrons, it forms a +3 ion (La3+). In this oxidation state, La has a noble gas configuration of [Xe]. Therefore, option B is the correct answer.

Other Oxidation States
Lanthanum can also form compounds in other oxidation states, but they do not achieve a noble gas configuration. For example, in the +2 oxidation state, La has an electron configuration of [Xe]5d1, which is not a filled outermost shell.

Conclusion
In conclusion, Lanthanum achieves noble gas configuration in the +3 oxidation state by losing three electrons and forming a La3+ ion.

Atomic number of Eu is 63...so electronic configuration of Eu is, Eu=[xe] 4f^9 Hence,Eu^+3=[xe]4f^6

Unlike lanthanides which show the +3, oxidation States,actinides show a variety of Oxidation State from +3to+6.However+3&+4 are the principal Oxidation State.The+3 Oxidation state is the most stable in AC and all the other elements of the series.Thats it.

Genetic Fingerprinting

Genetic fingerprinting or DNA fingerprinting is a technique used to identify individuals based on their unique DNA profiles. PCR and Restriction Fragment Length Polymorphism (RFLP) are two commonly used methods for genetic fingerprinting.

Polymerase Chain Reaction (PCR)

PCR is a powerful technique used to amplify a specific DNA sequence. It involves a series of repeated cycles of denaturation, annealing, and extension, resulting in the exponential amplification of a specific DNA fragment. PCR is used in genetic fingerprinting to amplify DNA from a sample, such as blood or tissue, and create multiple copies of a specific DNA fragment for analysis.

Restriction Fragment Length Polymorphism (RFLP)

RFLP is a technique used to identify variations in DNA sequences between individuals. It involves the use of restriction enzymes to cut DNA at specific sites, resulting in fragments of different sizes. The resulting fragments are separated by gel electrophoresis and visualized using a staining agent. The pattern of fragment sizes is unique to each individual and can be used to identify them.

Applications of Genetic Fingerprinting

Genetic fingerprinting has a wide range of applications, including:

- Forensic investigations: DNA evidence can be used to identify suspects or victims in criminal investigations.
- Paternity testing: DNA analysis can be used to determine biological relationships, such as paternity or maternity.
- Medical diagnosis: Genetic fingerprinting can be used to diagnose genetic diseases and identify carriers of genetic mutations.
- Evolutionary studies: Genetic fingerprinting can be used to study the evolutionary relationships between different species.

Conclusion

PCR and RFLP are two powerful techniques used in genetic fingerprinting. These techniques have revolutionized the field of forensic science and have a wide range of applications in medicine, biology, and genetics.

The actinoids are said to be most radioactive metals because in this group all the metals have very oxidation number and are very rare metals found on earth and it has all the elements radioactive in its group and it has most radioactive metal uranium in it's group.

Explanation:

Mischmetal is an alloy of Lanthanoid Metal and Iron. It is a rare earth alloy, which is primarily used in the production of alloy steels, stainless steels, and other high-performance alloys.

Composition:

Mischmetal typically contains 50-55% cerium, 20-25% lanthanum, and small amounts of other rare earth metals such as neodymium, praseodymium, and gadolinium. The remaining portion of the alloy is typically iron.

Properties:

Mischmetal has a number of unique properties that make it an attractive alloy for use in a variety of applications. These properties include:

- High heat resistance
- High strength and durability
- Corrosion resistance
- Good machinability

Applications:

Mischmetal is primarily used in the production of alloy steels, stainless steels, and other high-performance alloys. It is also used in the production of magnesium alloys, which are used in a variety of applications, including aerospace, automotive, and sporting goods.

Some other applications of Mischmetal are:

- In the production of lighter flints
- As a pyrophoric material for the ignition of torches and lighters
- In the production of certain types of electrodes for welding and cutting
- In the production of certain types of batteries

Conclusion:

In conclusion, Mischmetal is an alloy of lanthanoid metal and iron, primarily used in the production of alloy steels, stainless steels, and other high-performance alloys. It has a number of unique properties that make it an attractive alloy for use in a variety of applications.

Most human cells have 2 of each of the 23 homologous monoploid chromosomes, for a total of 46 chromosomes. A human cell with an extra set out of the 23 normal ones would be considered euploid. Euploid karyotypes would consequentially be a multiple of the haploid number, which in humans is 23.

For DNA fingerprinting special single stranded DNA-probes are made in the laboratory. DNA-probes contain repeated sequences of bases complementary to those on VNTRs. These probes are made radioactive by labeling with radioactive isotopes. This step helps in detecting DNA fingerprints or variable number of tandem repeats (VNTRs). 

The reason for this behaviour is a result of the stability of half filled, empty or fulfilled F orbitals that these elements achieve in these Oxidation State.Thats it.

Production of Magnetic Field

Magnetic field can be produced in various ways. The correct answer is option 'D', which states that a magnetic field can be produced using a permanent magnet or electric current. Let's discuss both of these methods in detail.

Using a Permanent Magnet

A permanent magnet is a magnet that retains its magnetic properties even in the absence of an external magnetic field. The magnetic field produced by a permanent magnet is due to the alignment of its atomic dipoles. The magnetic field produced by a permanent magnet is static and does not change in strength or direction over time.

Using an Electric Current

An electric current is a flow of electric charge through a conductor. When an electric current flows through a conductor, it produces a magnetic field around the conductor. The strength and direction of the magnetic field depend on the strength and direction of the current flowing through the conductor. The magnetic field produced by an electric current is dynamic and can change in strength and direction over time.

Conclusion

In conclusion, a magnetic field can be produced using a permanent magnet or electric current. While the magnetic field produced by a permanent magnet is static, the magnetic field produced by an electric current is dynamic and can change in strength and direction over time.

Actinoid Contraction and Lanthanoid Contraction

Actinoid contraction and lanthanoid contraction are terms used to describe the decrease in atomic and ionic radii of the elements in the actinide and lanthanide series, respectively.

Actinoid Contraction

- Actinoid contraction refers to the decrease in atomic and ionic radii of the elements in the actinide series.
- It is caused by the imperfect shielding of the 5f electrons by the 6s and 6p electrons.
- The 5f electrons are located closer to the nucleus and experience a greater effective nuclear charge, which leads to a smaller atomic and ionic radius.
- Actinoid contraction is observed in the actinide series from thorium (Z=90) to lawrencium (Z=103).

Lanthanoid Contraction

- Lanthanoid contraction refers to the decrease in atomic and ionic radii of the elements in the lanthanide series.
- It is caused by the imperfect shielding of the 4f electrons by the 5s, 5p, and 6s electrons.
- The 4f electrons are located closer to the nucleus and experience a greater effective nuclear charge, which leads to a smaller atomic and ionic radius.
- Lanthanoid contraction is observed in the lanthanide series from cerium (Z=58) to lutetium (Z=71).

Comparison of Actinoid Contraction and Lanthanoid Contraction

- Actinoid contraction is greater than lanthanoid contraction.
- The 5f electrons in the actinide series experience a greater effective nuclear charge than the 4f electrons in the lanthanide series, which leads to a greater decrease in atomic and ionic radii.
- Actinoid contraction is also observed over a smaller range of elements than lanthanoid contraction.

All the elements in the lanthanide series show an oxidation state of +3. Earlier it was believed that some of the metals (samarium, europium, and ytterbium) also show +2 oxidation states.

The lanthanides and actinides form a group that appears almost disconnected from the rest of the periodic table. This is the f block of elements, known as the inner transition series. This is due to the proper numerical position between Groups 2 and 3 of the transition metals.

The basis of identification by DNA Profiling is the polymorphism. ... These highly variable sequences of DNA are known as VNTRs (Variable Number of Tandem Repeats) and STRs (Short Tandem Repeats) often referred to as Minisatellites and Microsatellites. These are noncoding regions and are repeated within genes.