During menstruation period proper care regarding health and hygiene is needed rather than following myths.

What is true for "lactational amenorrhoea" ? i) It means absence of menstruation ii) Ovulation does not occur during the lactational period iii) Chances of contraception are almost nil upto six months following parturition iv) Side effects are almost nil v) Contraceptive efficiency reduces after the period of intense lactation vi) It is a natural method of contraception

Explain the following. (a) Why is the tungsten used almost exclusively for filament of electric lamps? (b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal? (c) Why is the series arrangement not used for domestic circuits? (d) How does the resistance of a wire vary with its area of cross-section? (e) Why are copper and aluminium wires usually employed for electricity transmission?

For a spontaneous reaction, the free energy change must be negative. DeltaG=DeltaH-TDeltaS is the enthalpy change during the reaction. T is absolute temperature, and AS is the change in entropy during the reaction. Consider a reaction such as the formation ofan oxide . M+O_(2) MO Dloxygen is used wp in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids consequently gases have a higher entropy than liquids and solids, in this reaction (entropy or randomness) decreases, hence is negative. Thus, the temperature is raised the DeltaS becomes more negative. Since, TDeltaS is subtracted in the equation, then SG becomes less negative. Thus, the free energy changes increases with the increase in temperature. The free energy changes that occur when one mole of common reactant in this case dioxygen) is we may e plotted graphically against temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. As per the Ellingham diagram of oxides which of the following conclusion is true?

For a spontaneous reaction, the free energy change must be negative. DeltaG=DeltaH-TDelaS is the enthalpy change during the reaction. T is absolute temperature, and AS is the change in entropy during the reaction. Consider a reaction such as the formation ofan oxide . M+O_(2) MO Dloxygen is used wp in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids consequently gases have a higher entropy than liquids and solids, in this reaction (entropy or randomness) decreases, hence is negative. Thus, the temperature is raised the DeltaS becomes more negative. Since, TDeltaS is subtracted in the equation, then SG becomes less negative. Thus, the free energy changes increases with the increase in temperature. The free energy changes that occur when one mole of common reactant in this case dioxygen) is we may e plotted graphically against temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. For the conversion of Ca(s) to CaO(s) which of the following represent the DeltaG vs T :

For a spontaneous reaction, the free energy change must be negative. DeltaG=DeltaH-TDeltaS is the enthalpy change during the reaction. T is absolute temperature, and AS is the change in entropy during the reaction. Consider a reaction such as the formation ofan oxide . M+O_(2) MO Dloxygen is used wp in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids consequently gases have a higher entropy than liquids and solids, in this reaction (entropy or randomness) decreases, hence is negative. Thus, the temperature is raised the DeltaS becomes more negative. Since, TDeltaS is subtracted in the equation, then SG becomes less negative. Thus, the free energy changes increases with the increase in temperature. The free energy changes that occur when one mole of common reactant in this case dioxygen) is we may e plotted graphically against temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. Which of the following elements can be prepared by heating the oxide above 400^(@)C ?

For a spontaneous reaction, the free energy change must be negative. DeltaG=DeltaH-TDeltaS is the enthalpy change during the reaction. T is absolute temperature, and AS is the change in entropy during the reaction. Consider a reaction such as the formation ofan oxide . M+O_(2) MO Dloxygen is used wp in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids consequently gases have a higher entropy than liquids and solids, in this reaction (entropy or randomness) decreases, hence is negative. Thus, the temperature is raised the DeltaS becomes more negative. Since, TDeltaS is subtracted in the equation, then SG becomes less negative. Thus, the free energy changes increases with the increase in temperature. The free energy changes that occur when one mole of common reactant in this case dioxygen) is we may e plotted graphically against temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. Free energy change of Hg and Mg for the convertion to oxides the slope of DeltaG . T has been changed above the boiling points of the given metal because

Amines are less reactive in substitution reactions. Their reactivity is much lesser than alcohols and alkylflourides towards substitution. Protonation of the amino group makes it a better leaving group, but not nearly as good a leaving group as a protonated alcohol. Protonated amino groups cannot be displaced by OH^(-) because it would react immediately with the acidic hydrogen which would convert it in to a poor nucleophile. The leaving group in quartenary ammonium ion has about the same leaving tendency as a protonated amino group but does not have acidic hydrogen. The reaction of a quartenary ammonium ion with hydroxide ion is known as Hoffmann elimination reaction. The leaving group is tertiary amine. Since a tertiary amine is only a moderately good leaving group, the reaction requires heat. The carbon to which the tertiary amine is attached is designated as alpha carbon. When the hydroxide ion starts to remove a beta H from a quartenary ammonium ion, the leaving group does not immediately start to leave because a tertiary amine is not a good leaving group. As a result, a partial negative charge builds up on the carbon from which the proton is removed. Which of the following statements are true regarding Hoffmann elimination ?

Following statements regarding the periodic trends of chemical reactivity of alkali metals and halogens are given. Which of these statements give the correct picture?

Some main group elements of s-block and p-block have family names as given in the following table. Observe the long from of a periodic table and complete the table with proper information.