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Multiple choice chemistry d- and f-block elements some important compounds of transition elements general properties of transition metals the d-and f-block elements
Mass (g)
Empty crucible $22.01$
Crucible and copper oxide $42.01$
Crucible and copper product $(1^{st}mass)$ $39.87$
Crucible and copper product $(2^{nd}mass)$ $38.01$
Crucible and copper product $(3^{rd}mass)$ $38.01$

Copper ions can have multiple oxidative states. The data table above was obtained during a lab in which an unknown copper oxide was heated in a crucible.
From this data, what is the name of the unknown copper oxide?

  1. Copper(I) oxide.

  2. Copper (II) oxide.

  3. Copper (I) peroxide.

  4. Copper (II) peroxide.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Subtract the mass of the empty crucible (22.01 g) from the final copper product mass (38.01 g) to find the mass of copper, which is 16.00 g. Subtract the copper mass from the mass of the crucible and copper oxide (42.01 g - 22.01 g = 20.01 g total oxide minus copper gives oxygen mass), yielding 4.00 g of oxygen. Calculating the mole ratio of copper to oxygen gives 16.00/63.55 = 0.25 moles of Cu and 4.00/16.00 = 0.25 moles of O, resulting in a 1:1 empirical formula of CuO, which is copper(II) oxide.

Multiple choice chemistry d- and f-block elements some important compounds of transition elements general properties of transition metals the d-and f-block elements
State True or False.
Fe$ _3$O$ _4$ is mixed oxide of FeO and Fe$ _2$O$ _3$. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Iron (II,III) oxide is the chemical compound with formula $Fe _3O _4$. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides, the others being iron(II) oxide ($FeO$), which is rare, and iron(III) oxide ($Fe _2O _3$) also known as hematite. $Fe _3O _4$ contains both $Fe^{2+}$ and $Fe^{3+}$ ions and is sometimes formulated as FeO ∙ Fe2O3. 

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Which of following hormone is produced by testis?

  1. Progesterone

  2. Estradiol

  3. Testosterone

  4. estrone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Testosterone is produced by testes. Testosterone, which is produced in the body by the male testes, influences men physically, emotionally and sexually. It is called the "king of hormones", testosterone is certainly the most important hormone when it comes to sexual characteristics in men.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Androgens are

  1. female sex hormone

  2. non steriod

  3. plant hormone

  4. male sex hormones
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Androgens are male sex hormones. The main androgen is testosterone, and an additional androgen is dihydrotestosterone. Testosterone is secreted mainly by the testes, but also a little bit by the adrenal cortex. In some tissues, testosterone is chemically changed into dihydrotestosterone in order to have an effect.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Which of the following is a steroid?

  1. Insulin

  2. Vitamins

  3. Cytokinins

  4. Estrogen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Estrogen is a steroid. Estrogens are a group of steroid hormones that control the development and maintenance of an individual's feminine characteristics. Natural estrogens exist in men as well as women, and are found in higher amounts in women, especially in those of reproductive age.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Which bond angle $\theta $ gives maximum dipole moments for triatomic molecule $XY _{ 2 }$ :-

  1. $\theta \quad =\quad 90^{ \circ }$
  2. $\theta \quad =\quad 120^{ \circ }$
  3. $\theta \quad =\quad 180^{ \circ }$

  4. Both 2 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For a triatomic molecule XY2, the dipole moment is the vector sum of individual bond dipoles. When the bond angle theta is 90 degrees, the vector sum of the two bond dipoles is maximized because the angle creates a sharper resultant vector compared to a linear 180-degree arrangement where the dipoles cancel out completely.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Deficiency of insulin in human beings causes:

  1. Blood coagulation

  2. Beri Beri

  3. Diabetes

  4. Dermatitis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Deficiency of insulin in human beings causes diabetes.


 Diabetes is a disease in which your blood glucose or blood sugar levels are too high, either because insulin production is inadequate, or because the body's cells do not respond properly to insulin, or both.

Option C is correct.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Point out the wrong statement about proteins.

  1. They are nitrogenous organic compounds of high molecular mass.

  2. They on hydrolysis by enzymes give aminoacids.

  3. Many of them are enzymes.

  4. They do not contain polypeptide .
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Proteins are nitrogenous organic compounds of high molecular mass which on hydrolysis by enzymes give amino acids. All proteins are enzymes. They do not contain polypeptide but are bonded by peptide linkage.