Silianol (SiH3OH) is more acidic than methanol (CH3OH) why?

We know that acidic strength of an acid also depend upon stability of its conjugate base. So silianol is more acidic than methanol (H₃C-OH) because conjugate base silianol (H₃Si-OH) stablised by dispersal of negative charge in H₃Si-O- ion by 2pπ—3dπ back bonding

Hence methanol is less acidic than silianol.

For more detail on Back bonding click here

Why Bond angle of NF3(102 degree) is lesser than in NH3 (107) ? explaine.

Bond angle of NF₃(102 degree) is lesser than in NH3 (107) as per VSEPR theory which suggests that in case of less electronegative terminal atoms like H, Bond pairs would be closer to more electronegative central atom, N and hence bonds open up due to repulsion between  bond pairs electron density in vicinity. But bond angle of PF₃(100) is greater than PH₃, its due to possibility of back bonding in PF₃ between lone pair of fluorine and vacant d-orbital of phosphorous (2pπ-3dπ) hence forth P-F bond acquires partial double character and we know well that multiple bonds causes more repulsion so bond angle is greater.

Explain C-H bond length of CH4 is longer than C-H bond length of Difloromethan (CH2F2) ?

Explain C-H bond length of CH4 is longer than C-H bond length of Difloromethan (CH₂F₂)  because according to bent rule more electronegative atoms decreases S-character in hybrid orbitals and the same time P- Character increases as results bond length increases for those hybrid orbital have more electronegative atoms and bond length of other orbitals decrease having less electronegative atom present hence C-H bond length of CH4 is longer than C-H bond length of Difloromethan (CH₂F₂) 

Related Questions:

What is Bent’s rule of hybridization?

Which of the following compound have longest (S=O)bond length , O=SF2, O=SCl2, O=SBr2.

Why Bond length of O-O is greater in H2O2 than O2F2?

How to arrange increasing (C-H) bond length in increasing order and H-C-F bond angle in the given compounds, CH4, CH3F, CH2F2 and CHF3 ?

BENT'S RULE OF HYBRIDISATION:

Which is more acidic Me3C-OH Or Me3Si-OH and why ?

Me3Si-OH is more acidic than Me3C-OH because after removal of H+ it's negative ions (Me₃Si-O-)stabilized by 2pπ—3dπ back bonding. While Me3C-O- is unstable than Me3C-OH.

B-F bond length in BF3 is shorter than B-F bond length in (BF4)- why?

B-F bond length increases when BF₃(130 pm) reacts with F- to form (BF₄)- [143 pm]. Its due to absence of Back-bonding in (BF₄)- hence B-F bond has completely single bond character