Unable to update my Ubuntu 16.04 LTS

I am trying to update the ubuntu by root@sachin-verma: sudo apt-get update It ignores all the packages like:

Ign:1 http://archive.getdeb.net/ubuntu xenial-getdeb InRelease Ign:2 http://archive.getdeb.net/ubuntu xenial-getdeb Release  ......                             Get:18 http://dl.google.com/linux/chrome/deb stable Release.gpg [819 B]                              Get:19 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease [109 kB]                         Get:20 http://security.ubuntu.com/ubuntu xenial-security InRelease [109 kB]           Err:18 http://dl.google.com/linux/chrome/deb stable Release.gpg                         The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E Get:22 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 Packages [1,201 kB] Get:23 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages [709 kB] .... Get:78 http://in.archive.ubuntu.com/ubuntu xenial-updates/multiverse DEP-11 64x64 Icons [14.3 kB]    Ign:78 http://in.archive.ubuntu.com/ubuntu xenial-updates/multiverse DEP-11 64x64 Icons              .... '  

My sources.list:

# deb cdrom:[Ubuntu 16.04.1 LTS _Xenial Xerus_ - Release amd64 (20160719)]/ xenial main restricted  # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://in.archive.ubuntu.com/ubuntu/ xenial main restricted # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial main restricted  ## Major bug fix updates produced after the final release of the ## distribution. deb http://in.archive.ubuntu.com/ubuntu/ xenial-updates main restricted # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial-updates main restricted  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## universe WILL NOT receive any review or updates from the Ubuntu security ## team. deb http://in.archive.ubuntu.com/ubuntu/ xenial universe # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial universe deb http://in.archive.ubuntu.com/ubuntu/ xenial-updates universe # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial-updates universe  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://in.archive.ubuntu.com/ubuntu/ xenial multiverse # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial multiverse deb http://in.archive.ubuntu.com/ubuntu/ xenial-updates multiverse # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial-updates multiverse  ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://in.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse # deb-src http://in.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse  ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. # deb http://archive.canonical.com/ubuntu xenial partner # deb-src http://archive.canonical.com/ubuntu xenial partner  deb http://security.ubuntu.com/ubuntu xenial-security main restricted # deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted deb http://security.ubuntu.com/ubuntu xenial-security universe # deb-src http://security.ubuntu.com/ubuntu xenial-security universe deb http://security.ubuntu.com/ubuntu xenial-security multiverse # deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse 

I am using the network provided by my company, Please help me how to resolve it.