$1\,kg$ of ice at $-10\,^{\circ}C$ is mixed with $4.4\,kg$ of water at $30\,^{\circ}C$. The final temperature of the mixture is ........ $^{\circ}C$ (specific heat of ice is $2100\,J/kg\cdot K$,latent heat of fusion of ice is $336000\,J/kg$,and specific heat of water is $4200\,J/kg\cdot K$).

If a copper rod carries a direct current,the magnetic field associated with the current will be

The $pK_a$ values of four carboxylic acids are $4.76, 4.19, 0.23$,and $3.41$ respectively. The $pK_a$ value of the strongest carboxylic acid among them is

Solution $X$ contains $Na_2CO_3$ and $NaHCO_3$. $20 \ mL$ of $X$ when titrated using methyl orange indicator consumed $60 \ mL$ of $0.1 \ M$ $HCl$ solution. In another experiment,$20 \ mL$ of $X$ solution when titrated using phenolphthalein consumed $20 \ mL$ of $0.1 \ M$ $HCl$ solution. The concentrations (in $mol \ L^{-1}$) of $Na_2CO_3$ and $NaHCO_3$ in $X$ are respectively:

In an optical fibre,the core and cladding are made with materials of refractive indices $1.5$ and $1.414$ respectively. To observe total internal reflection,what will be the range of the incident angle with the axis of the optical fibre?

Four positive point charges $+q$ are kept at the four corners of a square of side $l$. The net electric field at the mid-point of any one side of the square is (Take,$\frac{1}{4 \pi \varepsilon_0}=k$)